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