Here is the full list of all 17 Subnautica achievements. It takes around 40-50 hours to unlock all of the achievements on Windows.
Hatch and release a Cuddlefish
Build a prawn suit
Build a cyclops
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
Find the Degasi habitat in the deep grand reef
Build a seamoth
Repair the Aurora reactor
Build a habitat
Find the Degasi habitat in the jellyshroom caves
Find the Enforcement Platform
Find the Degasi habitat on the floating island
Dive for the very first time