Hawaii Iron Man for ultimate test.
We had a few people who did Ironman in our group who said this was way fucking harder. Ironman is a race and geared towards specific things. This is more just a slower grind
We had 2 marines quit. Another guy w me who was in pre-Ranger school said this was a lot harder than that.
When you add cold wet sandy dirty and 50lbs on your back, and pt, miles, etc - little things becoming things fast.