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.

Mariana Trench Treasure tells stories of her time living in the Trench. There was once a tale of a wonderful treasure, a treasure that Trench (for short) used to guard. She would guard it over long, cold and lonely days. But soon she left that cold, dark trench and moved to the lighter and warmer waters of lakes and rivers. She now lives with other water dragons like Aqua  Equus, Loch On, and another Deep Sea dragon hatchling named Deep Sea Salvage. For fun, she tries to pass off as legendary sea serpents like Nessy, Ogopogo or Champ, and she travels miles just to do so.

She never really talks to the other dragons, she rarely even surfaces from the water, but she is very kind. She loves to hang out with Deep Sea Salvage, and teach him to hunt for small fish or to get to the meat inside clams. Even though Trench has a large family of her own, it is with multiple partners, for she hasn't chosen a perminate mate yet. Alas, such a pretty leviathan can only hope.