A Humboldt squid rockets up out of the darkness, meeting Bob Cranston in the middle of a cloud of krill.

When Howard Hall graduated from college, he had a degree in zoology and a love of scuba diving. These days, he's combined the two interests into a successful career as a filmmaker.

Getting into the cavern network is no easy task. Unlike most Florida springs, which exit on land, Crystal Beach Spring emerges from the seafloor of the Gulf of Mexico.

Today Iron Bottom Sound is best known as a mecca for scuba divers, who can explore the dozens of war wrecks that litter its bottom.

When the quarry is Great Whites, Tigers, and other potentially deadly sharks, divers often descend to the sharks' territory in protective cages.