Muck diving

Slow hunting over sand, silt, and rubble for rare small creatures; Lembeh Strait in Indonesia is the world capital of muck diving.

Muck diving is diving over apparently barren bottoms, black sand, silt, rubble, even scattered debris, to hunt for small, rare, and bizarre creatures that live nowhere else. The distinctly unglamorous name comes from the terrain itself, but the residents are the most photographed animals in the ocean: mimic octopus, blue-ringed octopus, hairy frogfish, flamboyant cuttlefish, rhinopias, and nudibranchs by the dozen.

The technique is the opposite of covering ground. Move at a crawl, scan a meter of sand at a time, and rely on guides whose spotting skills border on supernatural. Buoyancy and fin discipline are everything, since one flutter kick can silt out the site and bury the subject; muck divers hover, use short frog kicks, and often carry a muck stick to steady themselves on bare sand without touching life.

Lembeh Strait in Indonesia is the acknowledged world capital, with Ambon, Anilao in the Philippines, Mabul off Borneo, and Dauin in Dumaguete close behind. Muck dives are shallow and long, ideal for cameras and for life-list keepers: a single Lembeh dive can add more species to your log than a week on a reef. Bring a magnifier, some subjects are smaller than a grain of rice.