Here is the full list of all 12 ABZU achievements. It takes around 3-4 hours to unlock all of the achievements on Windows.
Discover those that lurk in the abyss.
Discover the polar region.
Breach the water on the back of a blue whale.
Perform a flip while riding a creature.
Complete the adventure.
Ride the Great White Shark.
Burst 15 fish schools in the jetstream.
Leap from the water.
Witness predation while meditating.
Release fish from all the hidden pools.
Find all the meditation statues.
Add all secret shells to your collection.