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.

Sukeltaja is a silent deep sea dragon who rarely communicates with other dragons. He likes to stay close to his own kind, though, for he feels safe and pleasant that way. Others' presence is important to him even though he doesn't talk much, and he really cares about the ones who are near him. Instead of socializing, however, he prefers diving in the lake and exploring its depths. He finds submarine nature intriguing. His name "Sukeltaja" is a Finnish word meaning "diver".