2026 Washington Island
July 23 - July 25 |Washington Island, Wisconsin
Registration
All race registrations are completed online. We do not accept paper forms, do not offer race day registrations and do not accept payment from other services like PayPal or Venmo. You may register online by clicking here.
All Double ANVIL athletes (solo and team) are required to have our Medical Release Form signed by a licensed doctor. This form must be submitted to our race director via email one month prior to the race start.
Athletes may download the Medical Release Form here.
Race Categories
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Washington Island Mammoth Endurance 24 | 36 Hour Relay
July 23rd - July 25th
COURSE INFORMATION
Our courses consist of shorter loops inside a controlled area. The distance of our events require extra safety measures be taken to ensure athletes are cared for and able to receive medical help if needed while on course. These shorter loops allow for your family or crew to be much more involved in your race, resulting in an overall more enjoyable experience for athletes and their support crew.
The courses are inside a state park and are well marked / manned by volunteers during the event. Try it before you bash it - we guarantee you’ll find the shorter loops helpful and more enjoyable during your event.
Swim Course Details
0.25 miles (.402km) Open Water Loop
The swim takes place in a beautiful bay looking south from Gislason Beach. The water here is incredible - it's crystal clear, generally comfortable and usually sees a water temp of around 65 - 72 degrees. The area you will be swimming is considered a shallow body of water with water depths no greater than 8 to 9 feet across the swim course.
You will swim a 0.25 mile loop and then exit the water after each completed loop. Timers will be sitting at a table on the shore and it is important you exit the water, follow the loop around the timing table and communicate your race number with our volunteer swim timers. The swim course is open from 7:00am - 6:00pm Friday and 7:00am - 10:00am on Saturday.
A swimmer may use any swim stroke to propel themselves through the water and may tread water or float. You may not use any floatation device, flippers, or fins on the swim. Swim Caps are required at all times. We ask you to wear a brightly colored cap to help our lifeguards maintain good visibility on you during your swim. Wetsuits are allowed.
A kayaker or paddle boarder will be in the water at all times. We often have multiple "boats" on the water at once depending on the amount of swimmers in the water.
BIKE COURSE DETAILS
9.90 miles (15.932km) Open Road Bike Loop
The bike segment boasts some butter smooth roads, awesome sights and is generally a fast course. As it gets dark, you will be required to use adequate lighting (white light) on the front of your bike and a red flashing light on the rear. The front white light should broadcast decently 10’ or more. We also highly suggest a headlamp attached to your helmet. Ensure you have sufficient batteries to last throughout the night. There is electricity available to charge spare batteries inside the race village.
Although the course is referred to as a "fast course" it is not flat. In fact, there are two moderate climbs on the course. Please ride with caution. It is HIGHLY recommended you practice some night riding before making your way up to the event. All 36 Hour athletes are REQUIRED to begin and complete one loop of the bike course to begin the event unless you are race the 36hr run or swim. At the end of the day, cars are bigger than bikes so please stay alert and be aware of your surroundings.
Roads are OPEN and you must obey all traffic laws while on course. “Just like a training ride” is the mindset while on the route. It is the riders responsibility to know and understand the bike route. We do have glowing cones and reflective signs placed along the route during the entirety of the event.
Road bikes must be in good working order. Remember to inspect your bikes before the race so you do not have any mechanical surprises on the bike course. You may use more than one bike during the race.
You must wear an ANSI/Snell approved bike helmet during the bike course and have it buckled at all times when touching your bike. YOU MAY NOT DRAFT during this event. While on the bike segment, cyclists shall not work together to improve performance, efficiency, or position by teamwork or other joint conduct. All cyclists must assume and maintain a staggered riding position relative to the cyclists directly ahead.
No headphones are allowed. While you may carry a phone, you cannot use it for music on the bike.
Run Course Details
2.00 mile (3.218km) Out and Bike Run Loop
The run is on paved roads and takes you alongside the shore of Lake Michigan with plenty of shade but also a few sections of exposure to sun. Remember that roads are OPEN - please run with caution as vehicles will still be using the roadway. The course is flat as a pancake. There is literally zero elevation on the run course.
Crew is not allowed to be on course for support. All support must be done within the village. You may stop and rest at any time along the course, but the race clock is still in motion. Athletes may not receive any assistance in the form of transportation. You may not have your support crew pace you during the run.
Breaking my own rule: The stars are usually incredible on the island at night. We encourage you to break our headlamp rule for about 10 seconds. Make sure there are no cars around, stop, turn off your light and look up - the sky can be amazing!
Ready to test your limits?
Whether you’re chasing your first ultra or your next finish line, Mammoth Endurance is here to carry you through.