Full list of all 29 Nightmares from the Deep 2: The Sirens Call achievements. It takes around 8-10 hours to unlock all of the achievements on Windows.
Find all hidden octopi.
Finish all the games of Mahjong.
Finish half of all the games of Mahjong.
Finish a game of Mahjong in less than 1 minute.
Find all morphing parrots.
Complete the game.
Got to the contents of Davy Jones' chest.
Gather twelve golden fish tokens.
Finished all the puzzles without using the Skip button.
Finished all Hidden Object Puzzles.
Got to the top of the lighthouse and saw what's underneath.
Enabled your ally to return to work.
Prepare a spiked coffee.
Found your way inside the lighthouse.
Find all secret seahorses.
Finished 10 Hidden Object Puzzles in a row without any hints.
Fix the radio.
Find 4 Hidden Objects within 4 seconds.
Enter the shipwreck cemetery.
Tried to get through the labyrinth without the map.
Finished a Hidden Object Puzzle in less than 1 minute.
Finish any Hidden Object scene with less than 3 misclicks.
Saved your ally from a tight spot.
Find a direct way to get behind the closed gates.
Finished 5 puzzles in a row without using the Skip button.
Visited a local bar.
Finished a puzzle in less than 1 minute.
Witnessed the devastating attack of the sea monster.
Arrived on the pier.