Here is the full list of all 11 Storm Boy achievements. It takes around 0-1 hour to unlock all of the achievements on Windows.
Swim to the deepest part of the Ocean
Feed all 3 pelicans once
Play each Mini-Game once through the Remember menu
Say Goodbye to Mr Percival
Save the Sailors from a Sinking Ship
Have Mr Percival Fetch the ball from underwater 3 times
Leave an artwork on the beachfront
Stay underwater for the maximum amount of time
Have all 3 Pelicans get angry during the Feeding Mini-Game
Find 20 Cockles!
Change Direction in the Sanctuary Dream mini-game 15 times