Although I've been diving for many years now, one of the most thrilling dives I've done was in 2002 in the Melbourne Oceanarium. Oh, and did I mention the giant aquarium was full of sharks? Running through the middle of the aquarium is a clear plexiglass tunnel where visitors can view the pelagic marine life close up. But nothing beats dropping in from above and sinking gently to the 'ocean' floor. There, you can nervously enjoy toothy sharks swirling around you, considering you as possible meal material. Gulp!