Here is the full list of all 17 Koral achievements.
Get all collectibles in the seventh level
Unlock all collectibles
Reach your destination
Revive an enormus Coral Reef
Get all collectibles in the ninth leve
Get all collectibles in the eight level
Solve a puzzle in the dark
Leave the City Docks
Get all collectibles in the sixth level
Get all collectibles in the fifth level
Reach the sunken ship
Get all collectibles in the fourth level
Get all collectibles in the third level
Get all collectibles in the second level
Erase the first big polution barrier
Complete the first level
Get all collectibles in the first level