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