Fluorescing coral off the coast of Palau (© Norbert Wu/Corbis)

【April 26 2014】At 80 feet below the surface of the Pacific, in the reefs off the coast of Palau, some of the coral fluoresces in what little natural light reaches it. The coral absorbs light of one wavelength—which we perceive as a given color—and emits the light as a new color. Scientists still understand very little about the function of fluorescence among corals. Theories range from suggestions that it's a defense mechanism against predators to a form of sunscreen to guard against ultraviolet rays. Explore breathtaking Gallery from the HuluTrip homepage over the past 5 years..