Here is the full list of all 10 Submerged achievements worth 1,000 gamerscore. It takes around 4-5 hours to unlock all of the achievements on Xbox One.
Visit all of the hotels
Visit all landmarks
Gather all secrets
Gather all boat boosts
Finish the campaign
See all creatures
Climb to the highest point in the map
Stay in the boat for a complete day/night cycle
Visit the N/S/E/W boundaries
Use the postcard feature