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