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