Subterrel is a hot and toxic planet in the system and sector that bears its name. The planet itself is very hostile and requires expensive domes to be constructed to heal others from the toxic atmosphere. Even space suits are not sufficient enough, as there must be a lead coating to protect one from radiation that seems to be coming directly from the planet's core. It is unknown as to why radiation seems to be emitting from the ground, but it has caused the rock of the planet to glow. On top of that, even without sunlight, the planet remains very warm all year round, so warm that the rocks are nearly magma. In several areas on the planet’s surface, the rock has become so hot that it melted and collapsed. It formed large craters throughout the planet, and cooled down quickly, not keeping a permanent volcanic state.

This planet is also home to many caves, which is where several years ago colonists began setting up bases. The caves have long since been abandoned, but it is rumored that within the caves lies a vicious dragon that is able to survive off the mostly methane and acidic atmosphere. Apparently, this dragon has the ability to breathe acid breath, making it a deadly foe.