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