Try one of these out. I got one years and years ago. I would use it with a shuffle. There is a 3.5mm male inside the bag Then the 3.5mm female outside to plug your headphones into.
The bag itself has a double, heavy duty zip lock plus fold over to make it waterproof.
I have used it many, many times in the Lazy River at Blizzard Beach in Disney. Every time one enters and exits the volcano, one gets drenched in water. Haven't had a dap failure yet.
I think this bag with a Benji S5 and a KZ ZSR would be awesome. Or the KZ ZS1. Is that the iem that is like five bucks?
US Dollar prices...
13 for the bag, 26 for the Benji S5, 5 for some cheap iem. You are paddling in style for 45 bucks.
Large Water Resistant Ibagz..
https://www.amazon.com/dp/B000VE0G4K/ref=cm_sw_r_cp_apa_NnRsBbFJSRABS