Money belts are designed to be worn in the water and are waterproof.
It's, well, waterproof, not only in the shower but for those other fun activities, like rafting or swimming or kayaking. And in the rain.
If you're traveling solo, how many times have you wondered what to do with your valuables on the beach? If you've found new friends you can leave your stuff with them, but if you're truly on your own and your lodgings don't have a safe (it does happen) your choices are limited: you'll have to wear your stuff, and a waterproof pouch of some sort may be the only way to keep it all from getting soaked.
It's easy to keep clean and dry. Anyone who has ever used a concealed money belt made of cloth or synthetics will tell you how quickly it gets clammy and smelly. This one won't. Just run a soapy cloth inside and out and it's clean.
You can get waterproof phone cases as well.
Sold on the waterproof version? Remember you can get lots of styles - waist, of course, but also for the neck, wrist, leg, ankle and armband.