My husband and I have done this a few times. The sharks often stay at the bottom but there are always the ones up closer to the surface. I had one swimming alongside me basically last time and one swam head on at my husband on his first time into the tank. He was seriously chalk white when we got out of there! LOL Of course that may or may not have had something to do with me also grabbing his foot from behind right after that happened!
HA HA HA HA HA
Oh Man, I would have lost it if I was him. I bet you ran like the wind when you got out of the water.
I was a nervous wreck when we did it.