Sleeping Bear Dunes

https://www.nps.gov/slbe/index.htm https://en.wikipedia.org/wiki/Sleeping_Bear_Dunes_National_Lakeshore Sleeping Bear Dunes National Lakeshore is located along the northwest coast of the Lower Peninsula of Michigan in Leelanau and Benzie counties near Empire, Michigan. The park covers a 35-mile-long (56 km) stretch of Lake Michigan's eastern coastline, as well as North and South Manitou islands. This Northern Michigan park was established primarily because of its outstanding natural features, including forests, beaches, dune formations, and ancient glacial phenomena. The lakeshore also contains many cultural features including the 1871 South Manitou Island Lighthouse, three former stations of the Coast Guard (formerly the Life-Saving Service) and an extensive rural historic farm district. Miles of sand beach, bluffs that tower 450’ above Lake Michigan, lush forests, clear inland lakes, unique flora and fauna make up the natural world of Sleeping Bear Dunes. High dunes afford spectacular views across the lake. An island lighthouse, US Life-Saving Service stations, coastal villages, and picturesque farmsteads reflect the park’s rich maritime, agricultural, and recreational history. From the south (Detroit or Chicago areas) :Take US-31, US-131, US-27 to M-115 & M-37, I-75 and M-72 North to Traverse City, then west on M-72 to the Village of Empire. You will see the visitor center as you enter Empire on your right. You may also get to Empire from the south via US-31 to Ludington and then north to Manistee. You can follow either US-31 or M-22 from north of Manistee. From the north (Michigan's Upper Peninsula), take I-75 to Grayling and follow M-72 to Traverse City or take US-31 south Philip A. Hart Visitor Center The Philip A. Hart Visitor Center is located on M-72 just east of the intersection with M-22 in Empire, MI. You will find a wealth of information about the park and the natural and human history of the area. Park passes, brochures, and maps are available at the Information Desk. If you have questions, rangers and volunteers are available to assist you. From the south (Detroit or Chicago areas): Take US-31, US-131, US-27 to M-115 & M-37, I-75 and M-72 North to Traverse City, then west on M-72 to the Village of Empire. You will see the visitor center as you enter Empire on your right. From the north (Michigan's Upper Peninsula):take I-75 to Grayling and follow M-72 to Traverse City or take US-31 south to Traverse City, then go west on M-72 to the Village of Empire. Port Oneida Heritage Center The Port Oneida Heritage Center, at the Olsen farmhouse is operated by Preserve Historic Sleeping Bear, a nonprofit partner of the national park. During seasonal open hours the Heritage Center offers exhibits and artifacts in the farmhouse that tell the story of the late 1800s agricultural community of Port Oneida. The large barn is open and people can enjoy the gardens and a small museum store. South Manitou Island Visitor Center The former general store for the island now serves as a visitor venter. It houses an interesting collection of photos and artifacts that tell the story of what life was like for the loggers, farmers, and members of the Life-Saving Service who made the island home. Bay Campground - South Manitou Island The Bay Campground is the closest campground to the dock. Bring water filtration equipment because there is no source of purified drinking water. There are 25 individual sites and 3 group sites. Bay Campground for 1-4 persons 10.00 Nightly fee for Bay Campground for 1-4 persons Bay Campground Group SItes 30.00 Nightly fee for Bay Campground group sItes for 7-20 persons Bay Campground Tent on sand surrounded by conifer trees and grasses. Bay Campground D. H. Day Campground The rustic D.H. Day Campground is located in the northern district of the Sleeping Bear Dunes National Lakeshore, on the lower peninsula of Michigan. This beautifully wooded campground is one of the most popular in northern Michigan, with easy access to the Dune Climb, the Pierce Stocking Scenic Drive, and museums and the historic village of Glen Haven. and is located only 2 miles from the restaurants and shops of beautiful downtown Glen Arbor. Reservations only: May 1 – October 15 20.00 Reservations only: May 1 – October 15 National Park Senior or Access Passholders eligible for ½ price camping Additionally: A National Park Service entrance pass for Sleeping Bear Dunes National Lakeshore is required for each vehicle: $25 Sleeping Bear Dunes National Lakeshore entrance fee (1-7 days). $45 Sleeping Bear Dunes National Lakeshore Annual pass (if camping more than 7 days). Information about other National Park Service pass options can be found at www.nps.gov/planyourvisit/passes.htm Self-registration: October 16 - end of November 10.00 Self-registration: October 16 – Last Sunday in November National Park Senior or Access Passholders eligible for ½ price camping Additionally: A National Park Service entrance pass for Sleeping Bear Dunes National Lakeshore is required for each vehicle: $25 Sleeping Bear Dunes National Lakeshore entrance fee (1-7 days). $45 Sleeping Bear Dunes National Lakeshore Annual pass (if camping more than 7 days). Information about other National Park Service pass options can be found at www.nps.gov/planyourvisit/ Self-registration: First Friday in April – April 30 10.00 Self-registration: First Friday in April – April 30 (no water) National Park Senior or Access Passholders eligible for ½ price camping Additionally: A National Park Service entrance pass for Sleeping Bear Dunes National Lakeshore is required for each vehicle: $25 Sleeping Bear Dunes National Lakeshore entrance fee (1-7 days). $45 Sleeping Bear Dunes National Lakeshore Annual pass (if camping more than 7 days). Biking through DH Day Campground Woman on bike riding by a campsite. Biking in the campground D. H. Day Campground Group Campground The D.H. Day Group Campground offers more rustic camping. You will find dirt roads, vault toilets, and ready access to the Lake Michigan beach. There are no electric hook-ups or showers. The campground is located in the northern part of the park mid-way between Glen Haven and Glen Arbor. DHDCG group campsite for 7-25 persons 40.00 Nighlty fee for a DHDCG group campsite for 7-25 persons DH Day Group Campground Tent sprawl across the DH Day group campground Tent sprawl across the DH Day group campground Platte River Campground Platte River Campground is open year-round and offers a wide variety of camping styles. You can find back-in and pull-through sites for RV's, including electrical hookups; but it also offers beautiful tent sites, walk-in sites for the slightly more adventurous, and group sites (hike-in, tents only) accommodating up to 25 people. There is even a nearby backcountry campground for those who enjoy a great backpacking experience, but don't have the time to head for the Manitou Islands. PRCG campsite with electrical hook-up 31.00 Nightly fee for a campsite with electrical hook-up for 1-6 persons Additionally: A National Park Service entrance pass for Sleeping Bear Dunes National Lakeshore is required for each vehicle: $25 Sleeping Bear Dunes National Lakeshore entrance fee (1-7 days). $45 Sleeping Bear Dunes National Lakeshore Annual pass (if camping more than 7 days). Information about other National Park Service pass options can be found at www.nps.gov/planyourvisit/passes.htm PRCG campsite with no electrical hook-up 26.00 Nightly fee for a campsite with no electrical hook-up for 1-6 persons. Additionally: A National Park Service entrance pass for Sleeping Bear Dunes National Lakeshore is required for each vehicle: $25 Sleeping Bear Dunes National Lakeshore entrance fee (1-7 days). $45 Sleeping Bear Dunes National Lakeshore Annual pass (if camping more than 7 days). Information about other National Park Service pass options can be found at www.nps.gov/planyourvisit/passes.htm PRCG group campsites 50.00 Nightly fee for group campsites (hike in, tents only) for 7-25 persons. Additionally: A National Park Service entrance pass for Sleeping Bear Dunes National Lakeshore is required for each vehicle: $25 Sleeping Bear Dunes National Lakeshore entrance fee (1-7 days). $45 Sleeping Bear Dunes National Lakeshore Annual pass (if camping more than 7 days). Information about other National Park Service pass options can be found at www.nps.gov/planyourvisit/passes.htm PRCG Walk-in Sites 22.00 PRCG walk-in sites for 1-6 persons Additionally: A National Park Service entrance pass for Sleeping Bear Dunes National Lakeshore is required for each vehicle: $25 Sleeping Bear Dunes National Lakeshore entrance fee (1-7 days). $45 Sleeping Bear Dunes National Lakeshore Annual pass (if camping more than 7 days). Information about other National Park Service pass options can be found at www.nps.gov/planyourvisit/passes.htm Platte River Campground Ranger Station Ranger outside of the Platte River Campground Ranger Station Entering the ranger staiton. Popple Campground - South Manitou Island The Popple Campground is the furthest from the dock (about 3.5 miles), so you are likely to have fewer people camping there. The campground is close to the beach on the northern tip of the island. Bring water filtration equipment since there is no source of purified drinking water. There are 7 individual sites Popple Campground for 1-4 persons 10.00 Nightly fee for Popple Campground for 1-4 persons Popple Campground Wood sign that reads "Popple" in front of a trail and forest. Popple Campground Village Campground - North Manitou Island The small Village Campground contains eight first-come, first-served designated campsites, two fire rings and one outhouse. There is a limit of two tents and four people per site. Fires are permitted in the community fire rings at the Village Campground. Village Campground Campsites for 1-4 persons 10.00 Nightly fee for Village Campground campsites for 1-4 persons Village Campground Tent on sand surrounded by forest with a tarp tied above. Village Campground Weather Station Campground - South Manitou Island The Weather Station Campground overlooks Lake Michigan from the bluffs on the south side of the island. Camp sites are well secluded from each other and have fire pits for open fires. Follow the wooded trail past the lighthouse about 1.3 miles to the campground. Bring water filtration equipment since there is no source of purified drinking water. There are 20 individual sites and 3 group sites. Weather Station Campground for 1-4 persons 10.00 Nightly fee for Weather Station Campground for 1-4 persons Weather Station Group Campground for 7-20 persons 30.00 Nightly fee for Weather Station Group Campground for 7-20 persons Weather Station Campground Wood sign that reads "Weather Station Campground" in front of woody shrubs. Weather Station Campground White Pine Backcountry Campground This camp has 6 sites and is located about 2 miles from the Trail's End Road trailhead on the Platte Plains hiking trail south of Empire just off of M-22 and is about 1/2 mile from the Lake Michigan shore where you can obtain fresh water. There is no well water at White Pine, so if you use water from Lake Michigan, it must be treated before drinking it. White Pine backcountry site 13.00 Nightly fee for a White Pine backcountry site is $13. A National Park Service entrance pass for Sleeping Bear Dunes National Lakeshore is required for each vehicle: $25 Sleeping Bear Dunes National Lakeshore entrance fee (1-7 days). $45 Sleeping Bear Dunes National Lakeshore Annual pass (if camping more than 7 days). White Pine Campsite A blue tent nestled in the woods White Pine campsite Beach pebbles Sand and pebbles in foreground with turquoise water in background Lake and beach Lake Michigan overlook sun A bright sun begins to set into Lake Michigan Sunset viewing is a favorite activity--especially from the Lake Michigan overlook. Glen Lakes Overlook An overlook of two blue lakes surrounded by trees with fall leaves Glen Lakes overlook Empire Bluffs at Sunset A trail overlooking a large lake at sunset Empire Bluffs Trail Glen Haven Beach Waves crashing to shore with sand dunes in the background Glen Haven Beach Narada Lake at Sunset A stunning lake surrounded by the setting sun Narada Lake at Sunset North Bar Lake Sunset Dunes at sunset surrounded by two lakes North Bar Lake Sunset Glen Haven Village Historic District Landscape The Glen Haven Village Historic District contains examples of vernacular architecture, a nineteenth-century cordwood station, and steamboat stop. Originally a marine transportation company-operated village, Glen Haven provided goods and services for passing steamboats and later served as a tourist destination. The district is historically significant for the period 1864-1931. Two story Sleeping Bear Inn along a road in a bright snowy landscape beside Lake Michigan NPS Geodiversity Atlas—Sleeping Bear Dunes National Lakeshore, Michigan Each park-specific page in the NPS Geodiversity Atlas provides basic information on the significant geologic features and processes occurring in the park. [Site Under Development] dunes and lakeshore Great Lakes Mapping Great Lakes Network staff assisted Midwest Region staff in a mapping project that reveals a whole new way of looking at the Great Lakes parks. oblique view of the Gull Island shoal, Apostle Islands NL, Lake Superior NPS Structural Fire Program Highlights 2014 Intern Accomplishments Port Oneida Rural Historic District Cultural Landscape Port Oneida Rural Historic District at Sleeping Bear Dunes National Lakeshore is one of the largest and most complete historic agricultural landscape in public ownership. Beginning around the early 1860s, the site supported a lucrative lumber industry. By the 1890s, the decline in demand for lumber and deforestation motivated a transition to an agricultural-based economy. The agrarian community existed into the mid-19th century. A rural agricultural landscape with wooden farm buildings and open fields. Nighttime Navigation and Light Station Landscapes Lighthouses of the Great Lakes region are historic navigational aids that have guided sailors under dark skies, around dangerous coast lines, and through treacherous weather. The light station landscapes are an important cultural resource, representing developments in navigational technology and patterns of commerce and settlement. The landscape features suggest the lives of the keepers and their families who operated these lights, guiding ships through dark waters. Aerial view of a light station with cylindrical light tower, surrounded by trees and grass. First Ever Prescribed Fire at Sleeping Bear Dunes Sleeping Bear Dunes National Lakeshore conducted it's first ever broadcast prescribed fire on May 7. A wildland firefighter ignites a prescribed fire along a walking trail in a pine forest. The Mother Bear and Cubs of Sleeping Bear Dunes Sleeping Bear Dunes National Lakeshore honors a faithful mother bear. Dunes and dune grass Letter to the Editor The EPA updated its criteria for assessing water and sediment quality. This enabled a more nuanced analysis of water quality conditions in the Great Lakes. Our analysis suggests that parks would benefit from additional work on water clarity. Nearshore water quality monitoring station near Sand Island, Apostle Islands National Lakeshore Great Lakes Fire Management Zone Fire Departments receive much needed wildland fire supplies and equipment. Three Fire Departments protecting NPS units in the Great Lakes Fire Management Zone received over $95,000 in wildland fire equipment this year through the Rural Fire Readiness Grant. NPS and Burns Harbor Firefighters stand in front of donated fire engine Nearshore conditions in the Great Lakes national parks: A baseline water quality and toxicological assessment Field survey results suggest generally good water quality, although nutrient concentrations were unexpectedly high near several parks, and metals and legacy pollutants continue to affect sediments and fish. Nearshore water quality monitoring station near Sand Island, Apostle Islands National Lakeshore Fire Prevention Success--What’s Being Accomplished in the National Parks Sleeping Bear Point Life-Saving Station The Sleeping Bear Point Life-Saving Station (now the Maritime Museum) was built in 1901 to house the crew and equipment which would be called upon to save the lives of passengers and crew of ships in distress in the Manitou Passage. The U.S. Life-Saving Service was merged with the Revenue Cutter Service in 1915 to create the U.S. Coast Guard. US Life-Saving Service The United States Life-Saving Service (USLSS), the predecessor to the United States Coast Guard, formed in 1878. The story of the USLSS dates to almost 100 years before the service became an official agency, to the noble efforts of the Humane Society of the Commonwealth of Massachusetts, a group of affluent individuals seeking to prevent needless deaths from shipwrecks. A black and white photo of seven men wearing uniforms and standing in front of a boat house. Zehra Osman Zehra Osman has been a Landscape Architect with the National Park Service since 2001. Through her work at a variety of parks around the country, Zehra explores how cultural landscape documentation and research contributes to historic preservation and planning projects. A smiling woman in a green NPS uniform with arms crossed Wildland Fire in Red Pine and White Pine The red pine and white pine forest inhabits the cooler climates of the upper Midwest. They once covered large areas of northern Minnesota, Wisconsin and Michigan. Red and white pine forests owe their presence and persistence in large part to fire. Although both types of trees can live in areas without fire, especially on very sandy soils, frequent fires are necessary for healthy forests. Small flames consume dead pine needles and log under red and white pine trees. Boekelodge Log Cabin Cultural Landscape District The period of significance for Boekelodge is 1929 to 2005, corresponding to the original cabin construction and use of the land as a homestead, purchase and use by the Boekeloo family, and the purchase by the NPS and expiration of the use agreement. The cultural landscape contains beach, dunes, woodland, trails, buildings, and small-scale features. It was one of the last existing wilderness retreats, which were popular in the mid-20th century, in the state of Michigan. A log cabin to the right of a pond, which is surrounded by trees and grasses Series: Cultural Landscapes of Sleeping Bear Dunes National Lakeshore The cultural landscapes of Sleeping Bear Dunes National Lakeshore include a rural historic district, agricultural landscapes, homesteads and retreats, a light station, and a life-saving station. The documentation and care of landscape characteristics at these sites, within the natural environmental setting, helps to preserve a view of how the landscapes developed and were used over time. A wooden barn stands beside a smaller outbuilding with a stone foundation and gabled roof Protecting structures from wildfire at Sleeping Bear Dunes National Lakeshore During spring 2021, firefighters from the Great Lakes Fire Management Zone based at Indiana Dunes National Park, traveled to Sleeping Bear Dunes National Lakeshore to work toward protecting structures in the event of a wildfire. Firefighters near a woodchipper in a break in a thick forest. Changing Patterns of Water Availability May Change Vegetation Composition in US National Parks Across the US, changes in water availability are altering which plants grow where. These changes are evident at a broad scale. But not all areas experience the same climate in the same way, even within the boundaries of a single national park. A new dataset gives park managers a valuable tool for understanding why vegetation has changed and how it might change in the future under different climate-change scenarios. Green, orange, and dead grey junipers in red soil, mountains in background Things to Do in Michigan Find things to do, trip ideas, and more in Michigan. Dunes rise above shoreline under blue sky. Series: Things to Do in the Midwest There is something for everyone in the Midwest. See what makes the Great Plains great. Dip your toes in the continent's inland seas. Learn about Native American heritage and history. Paddle miles of scenic rivers and waterways. Explore the homes of former presidents. From the Civil War to Civil Rights, discover the stories that shape our journey as a nation. Steep bluff with pink sky above and yellow leaves below. NPS and Its Neighbors Create New Visitor Opportunities Thanks to the efforts of a National Park Service partnership with nonprofit organizations, local, and state agencies, Lakeshore visitors can now safely stroll, bike, and in winter months ski portions of the Sleeping Bear Dunes Heritage Trail. A 27-mile route linking the neighboring communities of Glen Arbor and Empire, Michigan, to visitor destinations within the National Lakeshore. A group of children and adults in winter coats use snowshoes to walk a snowy forest trail. Battle of the Bark Trees shade us from the sun, provide homes for wildlife, stabilize Earth’s surface, and produce food for humans and animals alike. Some are massive, and others are miniscule by comparison, but what makes one better than the other—we’ll let you decide! Check out our iconic trees below and find your favorite! Five thick barked red-brown trees are backlit by the sunlight. Songbird Monitoring at Sleeping Bear Dunes Summary of songbird monitoring data collected at Sleeping Bear Dunes from 2014 through 2018. Photo of a tan and brown bird with a long neck and a yellow bill standing in grass. Protecting Historic Structures from Wildfire in the Midwest Wildland Fire Success Story about hazard fuels reduction work to protect historic structures at parks in the Great Lakes Fire Managenmt Zone. New Life for Old Orchards in Port Oneida The Port Oneida Historic District in Sleeping Bear Dunes National Lakeshore contains 13 remnant orchards with many historic apple varieties. The orchards are preserved through an annual workshop with participation by NPS staff, partners, and community members. Originally starting in 2006 with pruning instruction, the workshop now includes the planting of grafted trees from a nursery that was established at one of the farms in the district. Blossoms and leaves cover the branches of a mature apple tree next to a two-story farm house Project Profile: Develop NPS and Tribal Native Seed Nodes in the Midwest Region The National Park Service will create two seed collection sites with plant propagation capacity within the Midwest Region that could be expanded with partner organizations, one at Wind Cave National Park and one at Sleeping Bear Dunes National Lakeshore. a roped off restoration area with bare sand surrounded by grassy dunes Outside Science (inside parks): Protecting Piping Plovers at Sleeping Bear Dunes National Seashore In this episode of Outside Science (inside parks), follow Scientists-in-Parks intern Natalia Portales as she joins the team at Sleeping Bear Dunes National Lakeshore to monitor and protect critically endangered Great Lakes piping plover. a title of Outside Science (inside parks) episode at Sleeping Bear Dunes Using fire as a restoration tool at Sleeping Bear Dunes In late May 2023, fire staff from the Great Lakes Fire Management Zone based at Indiana Dunes National Park, as well as firefighters from Sleeping Bear Dunes, the Michigan DNR, and the National Park Service Black Hills Wildland Fire Module came together at Sleeping Bear Dunes National Lakeshore to conduct the Good Harbor Prescribed Fires. A firefighter uses a driptorch to ignite a fire on the side of a road next to a wooded area. The Current: Spring 2023 The Spring 2023 issue of the Great Lakes Newsletter contains articles on the changing ways we produce and look at data, staff changes, the field season schedule, an overview of a project to look at songbird data from all three Midwest networks, and a listing of new publications. A white page with a black border at the top and the words The Current: Fall 2023 The Fall 2023 issue of the Great Lakes newsletter contains articles on planning for the future of the Inventory and Monitoring Division, retirement and departure of staff members, a summary of the Western Great Lakes Research Conference, a field season summary from each of our monitoring programs, and a list of new reports and publications. The front page of a newsletter, with a photo of a dragonfly perched on hiking boot. Amphibian Monitoring at Sleeping Bear Dunes, 2019 A summary of amphibian monitoring data collected at Sleeping Bear Dunes in 2019. A green frog sits on a floating mat of grasses. Amphibian Monitoring in the Great Lakes Network Parks: 2023 Update A summary of amphibian monitoring data collected in seven Great Lakes Network parks as of 2019. A light green and gray frog sits in the crotch of a tree branch at the trunk. Bat Monitoring in Great Lakes Network Parks, 2024 A summary of acoustic bat monitoring in Great Lakes Network parks from 2015 through 2019. A bat with large, round ears hangs from a rock. NPS International Activities Update, July - December 2023 During the second half of 2023, the U.S. National Park Service undertook many exciting international conservation projects. Following are summaries of notable cooperation between NPS staff and international counterparts between July and December 2023. Hemlock Woolly Adelgid Learn about the hemlock woolly adelgid in Sleeping Bear Dunes National Lakeshore! A hand holds a hemlock branch with small white egg sacs on the stem Bat Monitoring at Sleeping Bear Dunes, 2015–2019 A summary of bat monitoring data collected at Sleeping Bear Dunes National Lakeshore from 2015 through 2019. Eight round photos of individual bats, four on the top line and four below. The Current: Spring 2024 Spring 2024 issue of the Great Lakes Network newsletter, "The Current," featuring science stories, a farewell, the 2024 field season schedule, and recent publications. Woman wearing a backpack and carrying a GPS unit and a compass wades through water and shrubs. Series: #MyParkStory at Sleeping Bear Dunes How have the places that we all protect provided enjoyment, solace, inspiration, or other powerful experiences? Graphic of an eagle flying over a forest text National Park Week. April 20-28, 2024 #MyParkStory Volunteers Margaret and Patty Learn about Sleeping Bear Dunes volunteers, Margaret and Patty, and their work at the South Manitou Islands! #MyParkStory Volunteer Laura N Learn about Sleeping Bear Dunes volunteer Laura, and her work on the apple preservation project! #MyParkStory Volunteer Dave Card Learn about the work of Sleeping Bear Dunes volunteer Dave Card! #MyParkStory Volunteer Marvin Ivy Learn about Sleeping Bear Dunes volunteer Marvin Ivy, and his work on the barn restoration project! #MyParkStory Volunteers Joan Antle and Jeannie Corey Learn about Sleeping Bear Dunes volunteers, Joan and Jeannie, and their work with Friends of Sleeping Bear Dunes! #MyParkStory Volunteer Mary Lundeberg Parks run on volunteers! Allow us to introduce you to the incredible Mary Lundeberg. A group of five people stand on a beach. Three are NPS employees wearing the uniform Updated Species Database Will Help Boost Amphibian Conservation Across the National Park System To steward amphibians effectively, managers need basic information about which species live in parks. But species lists need constant maintenance to remain accurate. Due to recent efforts, the National Park Service now has an up-to-date amphibian species checklist for almost 300 parks. This information can serve as the basis for innumerable conservation efforts across the nation. A toad sits on red sand, looking into the camera. #MyParkStory Volunteers Jim & Bunny Jim and Bunny are full of love for park visitors and Sleeping Bear Dunes National Lakeshore. They recall many special volunteering moments and recommend it to others. How Pollinator Inventories Can Inform Park Management Decisions Pollinators play a crucial role in national park ecosystems and beyond. In the national parks, species inventories help managers know which pollinators are present, and in what abundance, to better understand the state of park ecosystems and make decisions about how to manage them. From 2024 to 2026, 17 parks across the country will be surveyed for bees and butterflies. Bee laden with pollen sits atop a purple flower. #MyParkStory Staff Craig Olsen #MyParkStory Staff Craig Olsen