I'd like to proclaim here that I got stuck in the Water Temple not for any of the 'normal' reasons. Behind the chest with the longshot is a block of time in the floor. Despite navi glowing green over it I did not realise at the time. In my stupidity I thought she was glowing green on an already opened chest. Why would that happen? I ran around the dungeon for ages not being able to work out what to do next.
I hate the water temple, and it's because of the amount of time I invested in it for no reason other than my own stupidity. Huzzah.