That one cave remix from vldc9 is pretty ambient, the one used in Night Swimming.
Haven't played the level yet, but the aesthetics look super solid.
EDIT: Played, it, and it's a pretty great level. The level looks incredible, and, while it doesn't exactly stretch the boundaries of creativity, it does what it wants to do fairly well without many issues.
And yes, the length isn't too bad. I think it could afford a little bit more at the end though.
Overall, the biggest problems were general feelings of claustrophobia, and the pink bubbles being instant kill were slightly annoying. I know that, if you make them tile 12F, it would be weird cause you could stand on it, but the instant kill nature of most of the obstacles mitigated the use of powerups slightly? I'm not sure.
I think the creativity in design could have been stretched slightly more. For instance, a few of the dragon coins weren't exactly hard to figure out... I personally prefer dragon coins that make you think
, rather than deal with precise obstacles. That way, it doesn't make an all dragon coin run feel twice as hard, but instead, it feels more rewarding.
Overall, the use of tile 1f0 was pretty well designed, but not exactly creative, which isn't a bad thing. There are some cases where I would raise the ceiling a bit, since it felt cramped sometimes.
So I would get rid of the red koopa here, as it's an annoying obstacle.
I don't think I liked the ending here. The bottom most bubble pretty much results in death, since you can't make it up. It's basically waiting and dodging enemies, and if you pick the wrong bubble to wait in, you could get screwed over.
I don't know what the point is of the bubbles down below in the orange platform puzzle thingy. If you take the bubble "route", instead of just falling down through the tile 1f0 sparkes, the floating carrot platform despawns anyway. Speaking of that puzzle, I didn't find it very hard to lower the platform.
And this puzzle, which I mentioned earlier, I believe could be made slightly trickier. I would remove the red urchins a bit, so it isn't so precise, and instead, maybe have the ground below have a layer 2 section that moves up and down, so you have to time throwing the red shell so it can hit the vine block. Difficulty through timing is usually more effective than precision, since it is a bit more fair, and can be learned quickly.
Overall though, I thought it was good!! To be honest, I thought it was more enjoyable and creative than turn block treeway. It could definitely stand to be longer though.