I'm bringing one of those synthetic chamois towels they sell for around $12 at places like REI and other camping/outfitter stores. They're about 1/8" thick, roll up to the size of a small T-Shirt, and soak up loads of water. They can be be wrung out to 98% of its water content, and then it's really light. I figure I can carry this around AC in a fanny pack and use it when I jump off the various docks as I hike up and down the caye.
I'm the guru of high-tech packing