If you are scuba diving, something like Otterbox is the only protection. However that itself is only rated to 120ft. if you go deeper, you are at the mercy of Mr Murphy.
All other $5-$8 dollar pouches etc at best will protect you if you were wind surfing or swimming. That is even at best.
My solution was to put my Dollars in my pocket. Even if they get wet, they are still useable and dry quickly in the glorious BON sunshine. And I clip the car and house key to my BCD. Nothing else is carried. (Oh yes, I have duplicate photopies of C/C and passport in the room, in case someone decides to walk away with the originals).
Thanks to everyone for the replies. ( 43 days and counting).
I use a small "dry bag" about 4 x 6" hung around my neck and inside my wetsuit. Into it goes the truck key, two pair of glasses, a $20 bill, driver's license and credit card. It all gets wet, always. The money still works, the credit card works, the glasses work and the key works. My advice -- go simple and cheap; expect everything to get wet.
We've had the best luck with the "Witz See-It-Safe Dry Case" in the small size, which is just big enough to hold your DL, CC, some cash, and a key or two but small enough to still fit into a BC pocket (and we always clip it to the BC as well) It has always kept the items dry and has never leaked. In fact, this is the only "wallet" my husband carries with him the entire time on Bonaire. We've tried many ways, but like this the best, and they're pretty inexpensive (about $7-$9)
We also just leave our sunglasses (cheap ones from the Dollar Store) towels, shirts, water bottles, and cheap flip-flops (again, from the Dollar Store) in the truck and so far have not had any problems.
Good luck and have fun!