I took the girls to Maui over winter break, and we ended up swimming one afternoon at a beach just south of Hanakao'o Park (NW coast). We had the extraordinary luck to be able to swim with these two guys (who I initially mistook for rocks until I saw them move):
I had time to grab a camera .. this photo is aiming straight down next to where I was standing:
Sea turtles are very graceful, and gentle, and they seemed reasonably content to tolerate us hanging out with them:
We grabbed our snorkel gear and swam with one of them for about 20 minutes. This turtle was massive:
This one is unlikely to be the one we were swimming with (we found her on the beach a little later), but you can get a sense of how big they are .. my guess is around 250 lbs and approx. 50 years old: