Illuminated by lights, the plankton reminded Mendy Dant of millions of fireflies dancing 15 feet below the wave surface in Keauhou Bay. As magical as they looked, however, they weren't the stars of what is arguably the Big Island's most spectacular underwater show.

With wings spread wide like birds in flight, two huge manta rays appeared from out of the darkness and somersaulted in front of Dant. As she watched, mesmerized, they fed on plankton, all the while gliding and twirling like ballerinas executing a graceful pas de deux.

“;It was the first time I'd snorkeled at night with the mantas, and the scene was so surreal,”; recalled Dant, vice president of Fair Wind, which has operated ocean tours along the Kona coast for 37 years. “;The mantas were magnificent but not scary or threatening. They didn't seem disturbed that we snorkelers were just a few feet away from them. Rather, it seemed like they enjoyed performing for us.”;

That memorable meeting took place last September during a test run for Fair Wind's Manta Ray Night Snorkel & Dive Adventure. The tour opened to the public the following month, and since then it has introduced nearly 1,000 visitors to the amazing mantas.

Just before sunset, participants board Hula Kai, a sleek 55-foot hydrofoil catamaran, for the memorable 2 1/2-hour excursion in Keauhou Bay. It's just a 10-minute ride to Manta Village, a quarter-mile offshore. There the cat anchors close to the tethered 2-foot-wide, 15-foot-long Manta Float, which Fair Wind constructed especially for this tour.

“;Bright lights that point down into the water are fastened on the float,”; said Kurt Bell, manager of Fair Wind's boat department. “;Snorkelers can hang onto the float, which gives them a sense of security and keeps them together. Meanwhile, divers descend as deep as 35 feet to the ocean floor to observe the mantas.”;

The float's lights attract the plankton, which, in turn, draws the mantas, which are primarily night feeders. They sometimes swim within inches of tour participants, the luckiest of whom see more than a dozen mantas during the 90 minutes they're in the water.

About 150 mantas live along the Kona coast, all of which have names. Angelika, Vallaray, Melainah and China are among those that frequent Manta Village.

“;Mantas are named by the person who first spots them,”; Bell explained. “;They're identified by the markings on their underside, which, like human fingerprints, are unique to each manta.”;

  FAIR WIND executives had discussed the idea of launching a night manta tour for several years because Manta Village, a well-known gathering place for the creatures, is located a short distance from the company's home port at Keauhou Bay.

Bell remembers his first manta dive there 18 years ago.

“;Several of them did tight backward loops right above me and my friends,”; he said. “;They have an incredible ability to bend their wings and bodies into an arc.”;

Because few opportunities exist for humans to get close to such large marine animals, Bell views the Manta Ray Night Snorkel & Dive Adventure as a special treat.

“;It's a once-in-a-lifetime thrill,”; he said. “;Snorkeling and diving are awesome activities in themselves, but when you enter the ocean at night, it adds a whole other dimension of drama, mystery and excitement. It's a peek into a rarely seen, little-known corner of nature's wondrous world.”;