The moon where the story takes place, home to the Blood Ocean. Blood Ocean: Other than the fact that it is composed of human blood, nothing is known about where it came from or how it remains in a liquid state. The ocean floor contains the remains of giant creatures and mysterious structures. The terrain consists mostly of deep trenches and complex, maze-like canyons. Because it is a sea of blood, light does not penetrate; visibility is only possible by taking photographs with a camera device, which produces grainy black-and-white images. Bizarre growths resembling seaweed are visible. There is dry land, but it is devoid of grass and consists of grey rock. The atmosphere is thin.

A massive creature inhabiting the depths of the Blood Ocean's trenches. Initially, only its cries are heard, and it remains unseen. Midway through, the cries grow louder, and it begins to appear as a mysterious shape passing by in photographs. When the protagonist reaches the final point and attempts to take a photo, the monster rams through the stern of the submersible and devours them. Based on various clues, it is presumed to be a giant fish-like creature.

Based on photographs of its eye, it appears to have a reptilian texture. Near the final objective, it appears as a persistent obstacle near the submersible, seemingly tracking the Iron Lung. If the player turns the vessel toward the obstacle and takes a photo, a giant eye staring directly at the submersible is captured. It then roars and disappears after a violent collision that causes heavy tremors. It appears only as an eye in the game's photographs. It is a different species from The Monster.

The submersible that Guest will pilot. It is an archaic vessel, shockingly primitive for a future where humanity has reached extra-solar planets. To withstand the pressure of the Blood Ocean, which exceeds its structural limits, the forward viewport has been plated over and the hatch has been welded shut. It lacks an internal oxygen generator or CO2 scrubber; even if the mission is completed, the pilot will suffocate unless someone opens it from the outside. The interior is divided into the bow, containing the controls and gauges, and the stern, containing the camera equipment. The control panel in the bow consists of a left side with a position gauge and horizontal arrow buttons, and a right side with X and Y axis gauges and vertical arrow buttons. The horizontal buttons adjust the vessel's angle, while the vertical buttons control forward and backward movement. The camera station in the stern features several gauges, a large square button, and a monitor on the left that displays captured photos. Opposite the photo monitor is a computer-like device called a Terminal, which allows for searching in-game lore.

A mysterious creature captured by Guest early on. An indigenous inhabitant of the Blood Ocean. A close look at its face reveals a human skull shape, and its fins appear to have human limbs attached, suggesting it is a fusion of humans from other submersibles. It possesses telepathic abilities and attempts to lure Guest toward a light leading to a divine being. However, upon realizing Guest's intent to return after retrieving data from the SM-8 submersible, it devours Ava's submersible, which was attempting to rendezvous. The Blood Eel then attacks Guest's vessel, but Guest forces an implosion in a desperate gambit, destroying the creature's jaw and killing it. It has numerous teeth, a grotesque appearance, and appears to have tentacles. It is larger than the submersible.