Subnautica

Subnautica (meaning "under the sea") is an underwater exploration video game played by Markiplier. It is followed by Subnautica: Below Zero.

Game Information
Descend into the depths of an alien underwater world filled with wonder and peril. Craft equipment, pilot submarines, terraform voxel terrain, and out-smart wildlife to explore lush coral reefs, volcanoes, cave systems, and more - All while trying to survive.