Now, there was already a topic for the question, but there wasn't a simple answer and it was also really old, so i decided to make a new one.
Basically, if you've played Banjo Kazooie/Tooie or seen videos of it, you've may have noticed that when going from one part of the area to the other the music would change based on which part of the area you went to. (e.g: Grunty's Lair in Banjo Kazooie and Isle o' Hags in Banjo Tooie are full of this.)
The same thing happens when going underwater, where the music will play a underwater version of the area's music.
So i'm wondering how to make it work, and if it does, make it seamless too.