Kailua-Kona, Hawaii — ONE big step off the boat and into the dark. When I hit the water, I feel all the familiar feelings, the ocean seeping into my wetsuit, the frantic bubbles on my face, the ineffable moment when the body's gyroscope switches over from gravity to buoyancy. But nothing else is familiar. I'm floating free in the blue-black ocean, a few hundred yards from Kona's volcanic bluffs. The water is about 40 feet deep here, but just a few hundred yards to the west the Big Island's seamount plunges into the miles-deep oceanic abyss.
A quarter moon silhouettes the dive boat Honu 1, where the dive masters are tossing out flashlights to their clients bobbing in the dark. Each diver has a couple of illuminated chem-sticks attached to his or her tank. Tonight the Honu 1's divers are wearing green chem-sticks -- the green team -- to distinguish them from the three dozen or so divers from other boats that are moored around us.
During the day, this area is known as Garden Eel Cove -- a more-or-less routine Hawaiian coral dive -- but at night the locals call it Manta Heaven. Here, attracted by the abundance of light-seeking phytoplankton, the Big Island's resident manta rays (Manta birostris) come to feed. It's a classic symbiosis: The divers bring the lights, the lights bring the plankton, the plankton bring the mantas, and the mantas -- huge but harmless creatures that swim in exquisitely slow arabesques in the spotlights, like dancers through an opium dream -- bring the divers from around the world, by the thousands.
This is the Big Island's famous Manta Ray Night Dive, frequently rated one of the top 10 dives in the world and pound for pound the most surreal encounter you are ever likely to have with a big marine animal.
"When people come back to the boat, they don't know what to say," Konahonu Dive Shop's Rich Sanchez told me earlier that afternoon. "One lady came up crying, saying she'd had a spiritual happening."
At about 8 p.m., my group's dive master, Tim Lenarsky, signals for us to descend. I bite into my regulator and squeeze the air-release button on my buoyancy compensator vest. Slowing sinking into the dark, with the faint, netted light rippling across the coral below, I can see in the distance the area they call the Campfire -- a rough circle of lava rock on the bottom where the divers place upturned underwater torches. A column of blue-green light glows from the bottom, and swirling above is a funnel of silver Hawaiian flagtails, like a small glittering tornado.
The divers are instructed to sit or kneel on the bottom and hold their lights over their heads, and as I level off and begin kicking toward the area, the scene reminds me of a movie premiere when searchlights sweep the skies above Hollywood. But then a manta flies through the beams and I think instead of London during the Blitz.
Manta rays are essentially winged gullets, and to see one swimming at you is to stare down the mouth of Creation. Mantas, which can grow to have a wingspan of 20 or more feet and weigh up to 3,000 pounds, are the largest rays in the ocean. Millions of years ago, these animals evolved away from their smaller bottom-feeding cousins, stingrays (which got a bad rap with the death of naturalist Steve Irwin), to become great oceangoing vacuum cleaners. The series of gill plates inside their maws incorporates mesh-like structures that collect whatever the animals scoop up -- plankton, fish larvae, copepods -- and moves it toward the esophagus.
Mantas (the name comes from the Spanish word for "cloak") were known to early mariners as devilfish because of the horned projections from their heads. These are, in fact, cephalic fins that help direct food to their mouths. There is nothing remotely threatening about mantas except their appearance.
I know all this before I settle myself on the sandy bottom (picking up a lava rock for added ballast) and yet the first time one of these animals sweeps out of the dark to buzz me, I get a lump in my throat. Because mantas are covered with a thin layer of protective slime, divers are not allowed to touch them (and doing so will get you kicked off the dive). Divers also remove their snorkels so that the mantas don't scrape their bellies on them. That allows the mantas to come within an inch or two of the divers. I feel water turbulence from the mantas' powerful wing strokes on my face.
Soon, drawn to the lights and the promise of thick zooplankton, four mantas come to the spot and begin wheeling and banking through the lights. The streams of divers' bubbles rise like fronds of sea kelp. Curious squirrelfish, brownish silver in daylight but red at night, swim up to my faceplate.