I’ll go first. In my opinion Ori and the Will of the Wisps does the water level just right. Luma Pools which is the water area/level does it just right where it’s not too frustrating, not too challenging but also super duper fun. And not to mention the area music is top tier too.
Super Metroid’s Maridia. You feel like you broke the game and accessed a secret area, and it’s beautiful and incredibly alien.