What to do with phones and wallets when I go swimming to a lake that has no lockers? So they are not stolen?

1. Ask people sitting close to you to care for the stuff, while you are in the water.

2. Stuff it deep down into your huge backpack.

3. Buy a water tigth device and take it with you into the water.

4. Put in a baby diaper (nobody likes to touch it).

5. One person stays behind on the blanket.