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