I ran the Kalalau Trial roundtrip this morning in 4:51:58, which appears to be a new fastest known time. I left Ke'e Beach at 5:53 am. My splits were 23 min at Hanakapi'ai River, 1:20 at Hanakoa River, 2:13 at Kalalau River, 2:21 at the waterfall at the end of the trail, 2:29 at Kalalau River, 3:26 at Hanakoa River, and 4:26 at Hanakapi'ai River. I saw a few backpackers, and I passed one couple trail running the whole trail. They were heading out around the 7 mile mark while I was heading back. Maybe they can "verify" my run if they happen to look up this website.
I was really lucky with the weather: clear, no rain, temperature in the 70's, and it didn't feel very humid for Hawaii in August. I'm not getting any consistent information on the dewpoint, but maybe it was around 60 degrees. I'm glad it wasn't wet, because I probably wouldn't have attempted the exposed section at 7 miles if the ground was soft.
My new Steripen stopped working after the first use, even though I tried to dry it out, so I had to use iodine and carry my collapsible canteen while the iodine treated the water. I only gave it 15 minutes, so hopefully I don't come down with anything! Rocked a fanny pack. I drank about 32 oz each at 25 min, 1:35, 2:30, and 3:41. I ate a Cliff bar at 2:35, a Pemmican bar at 4:00, and a few more bites of another Pemmican bar at 4:35.
Obviously a top trail runner like Max King would run this faster if he were going for speed, but now I understand why the FKT isn't faster, since I found myself slowing down or walking for safety on a lot of the trail.