I wonder why the need for "waterproof" speakers at all.
Waterproof, dustproof, sandproof, mudproof, connect wirelessly to your smartphone or tablet. Some can be used as charging banks for other electronic devices. Some are small enough to clip on your pack.
Take them to outdoor parties, picnics, beach, camping, backpacking, motor boating, yachting, and . . . obviously . . . on canoe and kayak trips to tick us off.