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