Ecco the Dolphin: Defender of the Future
I've put together my own version of the Ecco the Dolphin: Defender of the Future soundtrack, using audio I ripped from the game myself, as well as various sources on the internet.
Prototype Dolphins' World Championship Soccer Field
A while back, Caverns of Hope released a pre-release build of the game (Defender of the Future) which contained an entirely different soundtrack.
Included with that build is a document listing cheats, one of which unlocks all levels. I tried it, but noticed that Dolphins' World Championship was missing. I checked the disc image to make sure the level file was still there, and sure enough, it was. I then hacked the level list to replace Aquamarine Bay with Dolphins' World Championship. I was surprised by what I found...
It was definitely Dolphins' World Championship, but it looked like a soccer field! Here's a video showing my findings, if you don't feel like reading anymore.
To try it yourself, download the prototype linked above, as well as the patch. The patch includes xdelta3, the xdelta patch, and a script to apply the patch. Be sure you have enough disk space, because it will make a copy of the prototype's disk image! Once you apply the patch, load up the game in an emulator or burn the disc, and select Aquamarine Bay from the level select.