Here is the full list of all 17 Subnautica achievements. It takes around 40-50 hours to unlock all of the achievements on Windows.
Create and deploy a time capsule
Launch the neptune rocket
Cure the infection
Find the Primary Containment Facility
Find the Thermal Plant
Find the Disease Research Facility
Build a prawn suit
Build a cyclops
Hatch and release a Cuddlefish
Find the Degasi habitat in the deep grand reef
Repair the Aurora reactor
Find the Degasi habitat in the jellyshroom caves
Find the Degasi habitat on the floating island
Find the Enforcement Platform
Build a seamoth
Build a habitat
Dive for the very first time