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