The Marine VHF handhelds I’ve looked at were all waterproof. Mine was the Icom M72 Marine Transceiver.
Quote:
The IC-M72 offers Icom’s best-ever protection against water intrusion. This radio has been tested to survive after being submersed in 1.5m (4.9ft) depth of water for 30 minutes.

It doesn’t float (some radios do float), but it’s lashed to the flotation vest so it can’t get away; all the gear was attached with short lanyards. The PLB was lashed through its pouch to the vest.