Hello Igeere,
Unfortunately, I will be Rejecting your map.
The theme is somewhat original, there are some water/prismarine themed maps, but none exactly like this which is good.
The build is accurate to the theme, however it isn't very attractive to look at. I would recommend picking your theme based around an object that you can build, then incorporate the parkour into that, rather than having more of a room theme, as this will make your map look a lot nicer.
The parkour has variety which is good, but a lot of it still feels repetitive. Try to mix up your jumps a bit more throughout the map and try to avoid grouping your jumps. What I mean by this, is you would have a sequence of just ladders, then just regular blocks etc. Mixing it up a bit more and experimenting with other jump styles will make your map a lot more fun to complete.
The length and difficulty are good for a hard map.
Thanks for submitting your map! I hope to see more maps from you in the future.