Water Levels.
Water levels always seem to be the most frustrating in any game.
The Water Temple in Ocarina of Time. The even harder Jabu Jabu's Belly from Ocarina of Time. The yet even harder Water Temple in Majora's Mask.
Every water level in Mario 2D platformers.
Jolly Roger Bay and Dire Dire Docks in Mario 64.
The water world in Kirby 64.
Hell, even the Water routes in Pokemon games (There's probably a reason Water routes have been getting less and less present in each new region.
Water's unique properties usually mean that a water level is going to be incredibly frustrating and involving you being unable to use items/powerups, or redirecting water flow, or changing water levels, or swimming, with air running out, or walking more slowly, or just tonnes of other gameplay mechanics from hell.
