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 secrets
Finish the campaign
Gather all boat boosts
Visit all of the hotels
Climb to the highest point in the world
Visit all landmarks
Stay in the boat for a complete Day/Night cycle
See all creatures
Visit the n/e/s/w boundaries
Use the postcard feature