Here is the full list of all 35 Mysterious Island - there are A Hidden Object Adventure achievements.
To complete the level, find 4 old coins
To complete the level, find 5 old coins
To complete the level, find 3 old coins
To complete the level, find 1 old coins
To complete the level, find 2 old coins
To complete the level, find 3 hidden snakes
To complete the level, find 2 hidden snakes
To complete the level, find 5 hidden snakes
To complete the level, find 4 hidden snakes
To complete the level, find 1 hidden snakes
To complete the level, find the hidden bottles of Rum 1
To complete the level, find the hidden bottles of Rum 2
To complete the level, find the hidden bottles of Rum 3
To complete the level, find the hidden bottles of Rum 4
To complete the level, find the hidden bottles of Rum 5
To complete the level, find the hidden crab 3
To complete the level, find the hidden crab 4
To complete the level, find the hidden crab 1
To complete the level, find the hidden crab 2
To complete the level, find the hidden crab 5
To complete the level, find the hidden coconut 4
To complete the level, find the hidden coconut 2
To complete the level, find the hidden coconut 3
To complete the level, find the hidden coconut 1
To complete the level, find the hidden coconut 5
To complete the level, find spider 2
To complete the level, find spider 5
To complete the level, find spider 1
To complete the level, find spider 3
To complete the level, find spider 4
To complete the level, find the hidden board 3
To complete the level, find the hidden board 4
To complete the level, find the hidden board 5
To complete the level, find the hidden board 2
To complete the level, find the hidden board 1