I'm heading off on vacation soon, and I'm looking for a way to keep my stuff safe while I'm in the water. I don't always have a car with me where I can leave my valuables. I'm looking for some sort of waterproof bag or container that I can strap to my arm or otherwise attach to myself, that will fit one or two cell phones, a few cards or cash, and my keys.
I've found options that fit a cell phone (but really don't have extra room for anything else), or ones that could fit all I need to carry, but aren't rated as waterproof when submerged. I don't need to be able to use my phone - I just need to keep it with me, and dry (along with cards/money/keys).
Any suggestions would be very greatly appreciated!