This all feels a lot like that Korean web novel, The Tutorial is too Hard. I guess a lot of Koreans play computer games, so that's their frame of reference for writing novels/manhwa.
imagine tutorial levels where you can only progress if you have information/recipes from high level zones
another story where the author pulls everything out of his ass, and lets not even comment about how ridiculous this high psi magic water that can crush STONE
Sorry if some panels are messy to read, I have a full schedule since I have a flight on sunday, trying to get everything that I got laying around done before I leave.
The author should've made the water too acidic, basic or hot rather than base it on density. If the water is "that" dense, it should be easy enough to walk on (heck it should be in solid state but whatever).