Crystal Bay

Crystal Bay is Bali's box seat for Mola alexandrini, the giant sunfish that rises from deep water between about July and October to visit cleaning stations on the bay's outer corners. On a good morning the water is gin-cold and vividly clear, bannerfish flag the cleaning sites, and a disc the size of a dinner table materializes out of the blue with an entourage of divers trying to remember their etiquette. Outside mola season the bay is a pretty, sometimes-placid reef dive with turtles and dense coral bommies, plus a bat-filled cavern in the islet for variety. The channel corners deserve their hard reputation; this is a site where guides earn their keep.

The moment you come for: Seasonal ocean sunfish at cleaning stations; cold, clear upwelling water; coral gardens in the inner bay.

Topography: White-sand bay with coral gardens, a rocky islet, and steep edges falling toward the Ceningan Channel.

Current: The bay itself can be calm, but the corners toward the channel produce serious current and documented down-currents; mola dives push into exactly that zone.

Hazards: Down-currents at the corners have caused fatalities; thermoclines can drop temperatures abruptly below 20 °C. Dive with operators who brief abort procedures.

Conservation: A local code of conduct governs mola encounters, including approach distance and diver numbers; breaking it drives the animals off the stations.

Nitrox: Worth it here — profiles sit in the range where enriched air meaningfully extends no-stop time (with the training to use it).