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
Find the Primary Containment Facility
Cure the infection
Find the Thermal Plant
Build a prawn suit
Hatch and release a Cuddlefish
Build a cyclops
Find the Disease Research Facility
Find the Degasi habitat in the deep grand reef
Repair the Aurora reactor
Build a habitat
Find the Degasi habitat in the jellyshroom caves
Find the Degasi habitat on the floating island
Build a seamoth
Find the Enforcement Platform
Dive for the very first time