Deep Sea Dragons, as their name suggests, spend most of their time in the darkest depths of the sea. They have a bioluminescent dorsal spine that serves to attract prey and communicate with their own kind. As with many deep sea animals, they generally eat whatever they can manage to bait. They rarely leave the ocean floor, surfacing only during breeding season. When they do choose to travel to the shallower depths, they avoid bright lights and will only come up far away from shore.

Dragons are highly-intelligent reptilian creatures that—from a human perspective, at least—appear to live forever. Many different varieties of dragon exist, each with their own unique qualities, habitats, and behavior. Adolescence in dragons is usually marked by the growth of a hatchling’s wings, although not all breeds of dragons grow wings and some breeds have other traits that indicate the beginning of maturation. In Galsreim, dragons and humans coexist peacefully.

Oceanaeia is a Deep Sea dragon. Her affinity with ocean became clear even when she was an egg. The eggshell seemed to shrivel up on dry land, though it perked up when it was placed in the lake, and practically glowed when it was placed in salt water on PearlWave the Water dragon's suggestion. The egg hatched in a small aquarium holding salt water, and Oceanaeia's owner reluctantly released the hatchling into the deep ocean when it was old enough. She was sure that she would never see the dragon again. But that very night, Oceanaeia appeared in the family cave's lake. She had found an undersea tunnel leading to it. Now she is as much a part of the family as anyone else.