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