It's hard to say which level of Ocarina of Time I find more annoying - the Forest Temple or the Water Temple. Playing the first time, when I was... I dunno, pretty young (7? 8?), I managed to get stuck in both of them. The Water Temple I just gave up and left it, came back a year later and finished it with ease. But the Forest Temple... I got it done, but only after many hours of frustrated searching WITH THAT MUSIC GOING ON AN ENDLESS LOOP. I listen to that music now, there's a noticeable increase in my heart rate. Seriously, if you feel like torturing yourself, listen to that on a loop while doing some frustrating task.