I choose to do this FKT as I was in Kauai for the Kauai Marathon and couldn’t stay off the magnificent trails. I saw that Waipoo Falls is a popular rainforest hike in Koke’e State Park. Waipoo Falls, is a 800 foot waterfall that can be viewed from a number of lookout points(the day I went the massive waterfall was “turned off”, didn’t even know that was possible…but when I went back a few days later the big waterfall was still off but made it to swimming pool viewing area and turned at the sign there. It is a very straightforward out and back with a lot of climbing and people. The day I went a “search and rescue” team of 20 people was doing a stretcher carry out on trail so slowed me a bit waiting for them and also passing lots of hikers. It was fantastic to show what is possible and had a lot of people cheering. Really enjoyed it and know that time can be bettered. Hope you tackle this challenge and can’t wait to see just how quick you can go. I would go earlier in day also as I had to wait as had a shake out run for Kauai marathon first. You don’t really need water even in heat as quick. Good luck