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