Water Purifier: Since all your neighbors' stank will be floating in the water, you'll want to use a purification system before you take a swig. Get a small and compact one, as well as some empty jugs to put the water in.
This didn't take long to clean, but the students used my personal water buckets for this. They were returned, but all of them were damaged beyond repair.
Waders & Boots: You'll be trekking through water of varying levels, so have some waders and waterproof boots on hand. Waterproof socks are also great items.
Wet Suit: If the waters are at an extreme level, a wet suit can be beneficial, for warmth, protecting your skin, etc. And for mobility's sake, a pair of flippers can give you some needed speed.