Bring two bathing suits. Nice to get into a dry one each morning. Unless you have lots of energy for changing, you will be in a bathing suit all day. Bring fins with boots. I tried using full foot fins on my last trip and injured my foot badly getting out of the water ON THE FIRST DIVE. That was the only bit that sucked. Dramamine and just use it the first day. Really. You’ll be happier. Two pairs of shoes, one of them Teva like. If you walk around in one, often damp, pair of tevas all week, you will have hot spots on your feet. If you walk around all week in your dive boots, you will be writing poetry about the sinister smells of warmly rotting sea monkeys... Bring Sudafed. Long t-shirt for jammies.
No Bring: hair spray, more than two pairs of underwear (bathing suit all day) Unless you really need to struggle into them after that last shower for the last hour before you collapse happily into bed (no really, have you tried putting underwear on to your slightly damp body? I gave up on it after about 12 hours on the first trip), socks, food (unless you have special requirements the boat can’t handle), anything delicate that will be broken by being tossed around or anything you would miss if it got thrown from the boat (think heavy or connectible), jewelry, leave the cologne/perfume at home.