• Location: Island located at the eastern end of the Straits of Mackinac in Lake Huron, one of the Great Lakes of North America.
• Course: Normally a flat-water swim unless strong wind conditions occur
• Distance: 12 miles around the 3.8 square miles or 9.8 square kilometer island
• Date of Annual Race: Great Turtle Relay Swim Around Mackinac Island is held in July
• Description: First circumnavigation completed in 2004 by Dick Buist, Dennis Barber, Dave Newton and Ed Gilde completed the first circumnavigation relay swim in 5 hours and 11 minutes. A National Historic Landmark, the island is small and part of the state of Michigan and is can be done "carbon-neutral style" (i.e., relay swimmers rotate in the water every 20 minutes. When it is not their turn to swim, the swimmers walk around the island. Each relay member swims for 20 minutes and then walks for 60 minutes until they finish the approximately 11-12 mile circumnavigation of Mackinac Island) in the 63˚F (17˚C) water.