I just came back from Belize, where I went kayaking, snorkeling and bike riding. I used a combination of cargo pants (or shorts) and a small fanny pack (about $7 from Walmart). I had more than enough room for my passport, survival items and a digital camera.

For organization of the survival items, I used one or two dice bags from here:
http://www.coolstuffinc.com/main_supplies.php?viewType=Dice%20Bags&info1=Dice&info2=Bag

For protection of my passport, I used either a Ziploc bag or this waterproof hard case:
http://www.amazon.com/Witz-Passport-Locker/dp/B001AQN2LW

Again, everything I needed easily fit into the cargo pants and fanny pack. I could have fit everything in my cargo pants if I had to do so.