In the late 22nd century, the mining vessel Aurora traveled to Planet 4546B on a mining and exploration mission. In fact, the Aurora also carries a mission unknown to most of the crew - to rescue the survivors of the shipwrecked ship Degas ten years ago. However, the Aurora was attacked by an unknown weapon while traversing the atmosphere of 4546B, and crashed on the planet 4546B. The protagonist of the game successfully escapes in an escape pod, and when the protagonist climbs out of the escape pod, he finds that the entire planet is covered in water, so the protagonist's survival and exploration in the deep sea begins.