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.

Tethys lives in the abyssal zone, the depths to which light doesn't penetrate. She only comes to the surface once a month to mate with her love, a skywing named Qereq. Her second greatest love is exploring shipwrecks. She relies on her mistress to point her in the right direction because the ocean is so vast, but when she does find a wreck, she spends days exploring every inch. She loves both the light and the dark because she believes each gives her a different way to see the world. As her light is often too dim to see much of the shipwrecks she uses echolocation to paint a vivid picture in her mind. But all of that was before children. Now that she has hatchlings, she spends most of her day protecting them and bringing them food. Her mate is very willing to help her, but it is hard for a skywing to watch a deepsea hatchling. When he does, she takes this time to return to a wreck she previously explored to recapture her glory days, but she no longer has time to discover new wrecks.