Here is the full list of all 22 Sea of Solitude achievements.
Shooed all Seagulls
Collected all bottles
Swam a very long distance
Swam a long distance while Whale was around
Eaten by Whale 20 times
Got grabbed by waterhands 10 times
Respawned on couch in Skyscraper
Jumped headfirst into the water from a high point
Finished the game
Finished Level 3
Finished Level 2
Reached top of the Skyscraper
Travelled a long distance by boat
Finished Level 1
Travelled very far by foot
Made it through school
Fired 30 flares
Opened a path through water
Collected your first Message in a bottle
Shooed your first Seagull
Connect with mirror Kay for the first time
Fired the first flare