Subnautica 2

Unknown Worlds' underwater survival game strands you on an alien ocean world after the colony ship CICADA goes wrong. It is a single-player game that can be played in co-op with up to three friends, from four pre-designed characters. The Tadpole submersible is how you cross biomes, and bases are what let you stay out past the safety of shallow water. Scanning is the progression: study everything from the smallest creatures to the Leviathans. It is in Early Access, and Unknown Worlds say so plainly — expect bugs, in-development features and performance issues while biomes, creatures and craftables are still being added.