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.

In the darkest depths of the cold and far away sea live the Deep Sea Dragons, mysterious creatures with snake-like body; they are rarely seen on the surface, and then pass almost always unnoticed to humans, but every now and then it happens that a boat could meet them during the mating season. Once a vessel crew member reported of having seen a "Neidr Dyfrol", which means literally a water snake, but it was a moonless night, while the sailor was pretty tipsy, no one else saw them and then everyone thought of just a crazy nightmare.

Heledd does not really like very large groups of Deep Sea Dragons, preferring instead to swim alone with his childhood friend and life mate Goronwy. This couple is deeply bound, because they know each other since ever and would never think of living apart, indeed, now the two are even thinking of expanding their family...