I got one of these and have been very impressed. I think it was Flojo here that mentioned this unit.
I use it in the shower, my 911, my Scout and by the pool. I can hear music driving down the highway in my Scout with the roof on and that is saying something !
https://www.amazon.com/Ultimate-Ears-MEGABOOM-Bluetooth-Waterproof/dp/B07DD3W154