On this page of the Returnal game guide, you will find a list of all six biomes of the planet Atropos.
During completing the Returnal game, you will visit 6 different biomes. They will be not only different environments but also the alien creatures that inhabit them will vary. At the end of each area of the planet Atropos, there will be a fight with the boss (with one exception).
Below is a list of all biomes of the game Returnal: