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.
Discover those that lurk in the abyss.
Breach the water on the back of a blue whale.
Discover the polar region.
Witness predation while meditating.
Release fish from all the hidden pools.
Find all the meditation statues.
Add all secret shells to your collection.
Complete the adventure.
Ride the Great White Shark.
Burst 15 fish schools in the jetstream.
Leap from the water.