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