National Geographic : 1997 Jan
DELIGHTS OF THE DARK For Australian marine biologist Karen Gowlett-Holmes (right), diving in Cathe dral Cave is a religious experience. And a dangerous one. Part of the largest sea cave system in Australia, this Tasmanian maze can safely be explored only during calm seas. "A heavy swell can trap you in the back of the cave or shoot you up 20 feet in a heartbeat," Karen says. It's worth the risk. The cave's walls are upholstered with vivid sponges, soft corals, and other invertebrates fed by the rich broth borne in on strong currents. Ample food and dim light allow some creatures normally found below 300 feet to thrive in these shallower depths. In the winding darkness we spot a rare Ziebell's handfish crouching in a copse of orange sponge (below right). Near the cave's mouth, red handfish grip the sand (below). Found only in southeastern Tas mania, these fish rarely swim, instead us ing handlike pectoral fins to walk, grasp the substrate, and brace against the surge-much like the panicky dance of human hands in a lurching subway car.