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.
Gather all secrets
Gather all boat boosts
See all creatures
Visit all landmarks
Visit the N/S/E/W boundaries
Climb to the highest point in the map
Visit all of the hotels
Stay in the boat for a complete day/night cycle
Finish the campaign
Use the postcard feature