A sheltered bay of extraordinary clarity on Australia's south coast — declared the clearest water in the Southern Hemisphere — where summer nights bring spectacular bioluminescent plankton that light breaking waves electric blue.
The sand at Hyams Beach on the southern shore of Jervis Bay holds a Guinness World Record: the whitest beach sand in the world. Silica so pure and fine that it reflects light as brilliant white. Against the bay's turquoise water, the effect is Caribbean in appearance but geologically Australian. The water clarity is a consequence of geology and ocean current. Jervis Bay is sheltered from the open Tasman Sea, and the upwelling of cold, nutrient-poor water keeps the bay clear. Visibility underwater regularly exceeds 15 meters. But the phenomenon that brings people in summer is different. Between December and February, bioluminescent phytoplankton bloom in the bay. When disturbed by wave action, each organism emits a brief blue flash. In the dark, breaking waves light up from inside, each surge of white water edged and filled with electric blue. Swimming in the bay on a bioluminescent night is one of those experiences that resists description.