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