Underwater 'Twilight Zone' – Blackwater dives take place in the dark of night. Diving photojournalist Doug Perrine took these incredible images during a dive off Kailua Kona on the coast of Hawaii's "big island."
Unseen animals – "There's something really special about being out there and knowing that there's a whole world of animals below you that nobody's ever seen," says diving expert Jeff Milisen.
Mesopelagic zone – "This is the world's largest migration," says marine biologist Sarah Matye, "and it happens every night. These animals are coming up from the mesopelagic zone."
Sci-fi scenes – Jeff Milisen says the appeal for some is the dives' "Star Trek" aspect. "For others, it's the phenomenal feeling of discovery and exploration."
Unique experience – "This is the most unique dive you will ever do," Sarah Matye says. "Often times we are seeing things that are totally new to science."
Gelatinous – Matye and Milisen are in constant communication with scientists who study the sorts of gelatinous plankton, juvenile fish and invertebrates that float about in Kona's surface waters at night.
New finds – Mayte and Milisen say they've photographed and collected several species that have never been recorded before.
Exclusive excursions – Vacationing divers pay top dollar for the night dives -- between $150 to $200 per dive.
Deep ocean – Off Kailua Kona, the dives involve trips out into the deep ocean. Divers are shackled to a free-drifting boat for safety.
Sub aquatic cosmos – For divers, the blackwater experience can be one of traveling through a limitless cosmos, as miniature moons, galaxies, and alien creatures drift past.