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.
Add all secret shells to your collection.
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.
Witness predation while meditating.
Discover those that lurk in the abyss.
Burst 15 fish schools in the jetstream.
Leap from the water.