Ever wondered what creatures lurk in the dark waters of Hawaii at night? Well, you’re in for a treat. Underwater photographer Jeff Milisen has produced an incredible assortment of images taken during night dives with Kona Honu Divers off the coast of Oahu.

Compiling his images in a collection called Blackwater, Milisen groups his favorite nocturnal ocean dwellers into three categories: larval fishes, cephalopods, and miscellaneous critters. The “alien life forms”, as Milisen describes them, glow bright against a black background, often using bioluminescence to make themselves visible in an otherwise pitch-black world.

Bioluminescence – the ability to produce one’s own light – is a superpower used by various creatures, from teeny glow worms to the colossal squid. It’s particularly prominent in marine creatures that live at depths that sunlight can't touch. Producing your own light comes in handy for all sorts of things, from flirting with potential suitors to luring tasty prey straight into your mouth. Producing bright flashes of light is also used by various deep-sea beasties to frighten and confuse predators.

“Some squid and lanternfishes have even been shown to vary the brightness of their ventral photophores to mimic the brightness of the moon,” Milisen writes on his website. “Many fishes combine counterillumination with highly reflective surfaces that reflect the ambient shade of blue back at any would-be predators.”

Here are some of our favorite Blackwater photos.

This funky little octopus is a juvenile between its larval and sub-adult life stages. It belongs to a genus called Callistoctopus, a group of orange octopuses that emerge at night. They share their habitat with other octopuses that operate in daylight hours, so they have adapted to a nocturnal lifestyle to reduce competition for food.       

The mahi-mahi, sometimes referred to as the common dolphinfish or dorado, can grow to weigh a whopping 22 kilograms (48 pounds) and is found across the world. This one is just a baby.

This stunning critter is a shrimp belonging to the family Penaeidae, which includes tiger prawns and whiteleg shrimp. Many invertebrates are transparent as a clever form of camouflage.

This weird-looking little guy is the larval form of a gurnard fish, aka a sea robin. The adult fish are bottom-dwellers and sport some rather funky, fan-shaped fins. The nickname "sea robin" comes from the adult's brilliant orange coloration.  

Below you can see two bigfin reef squid. They are known for their large fin that pretty much encircles their whole body. Their bodies are covered in chromatophores, light-reflecting cells that contain pigment, which allow them to match their surroundings.   

This bizarre ocean alien is a young sharpear enope squid. These creatures are found around the world and dive down to around 700 meters (2,200 feet). They use bioluminescent counterillumination to hide from predators.