All of the above. I like sector 4 because it doesn't force you to go through the water until you get the gravity suit. And sometimes, swimming can be a pain.
I don't really know what you're asking in the second sentence though?
Lakebed Temple was fantastic, and innovative. It was not hard either. I can understand Water Temple, but Lakebed was pie. Maybe you just need to get back in there and try if again. Now mister!
Poor you. Going into that deep water with no Gravity Suit. No wonder. I am sorry for your loss.
I was shocked when the water drained from the room and I realized how large Morpheel's chamber actually was. He is one of the largest bosses in the series.