Here is the full list of all 10 Submerged achievements. It takes around 4-5 hours to unlock all of the achievements on Windows.
Gather all boat boosts
Gather all secrets
Finish the campaign
Climb to the highest point in the world
Visit all landmarks
Visit all of the hotels
See all creatures
Stay in the boat for a complete Day/Night cycle
Visit the n/e/s/w boundaries
Use the postcard feature