In the waters off the Hawaiian Islands, odd, black-and-white creatures glide through the dark nighttime sea. These big, strange animals are manta rays, largest of the ray species. As part of filming for America's Underwater Treasures, a two-hour special on the National Marine Sanctuaries and an episode of the PBS series Jean-Michel Cousteau Ocean Adventures, Fabien and Céline Cousteau ventured into the inky depths to get an up-close look at these gentle giants. As the Cousteaus descended into the darkness to observe the manta rays, plankton were drawn to their underwater lights like moths to a flame, and so too were the mantas rays to feed on the dense concentrations of plankton. Soaring in like alien spacecraft, mouths agape, the manta rays skimmed the water just over Fabien and Céline's hand-held lights, and gracefully evaded the divers.