Everytime i swim somewhere deeper, like a river, a water puddle or in the sea,
every time the underwater music starts playing. If other Music played at the moment, this stops instantly and the Underwatermusic starts playing. But it wont go away. If you step out of the water, it keeps playing. In my opinion, this doesnt make any sense, it is underwater music, which should start playing if you are swimming in the sea, but if you get out and go away, it should stop playing. It isnt the right feeling to go through a desert with Underwater Music playing in the background. 
By the way, the water splash sounds are still the old ones from a few years ago and were never updated in Bedrock edition.  (Java Edition has new ones since 2 years)

Steps to reproduce:
Look for a river/sea
Hop in
Swim a bit underwater (U should hear the Underwatermusic starting to play)
get out and go away.

You will see, that the Music keeps playing and only stops, until the complete track is done.