Here is a 100% walkthrough of Chapter 2: The Sea including all the secret locations and the missable achievement
Eagle Eye.
Secret / Collectible #1 - 1:36 (Eagle Eye Achievement)
Secret / Collectible #2 - 2:43
Secret / Collectible #3 - 3:54
Secret / Collectible #4 - 5:00
Secret / Collectible #5 - 11:20
Follow along the video to also unlock:
The Eagle eye achievement in Unravel worth 75 pointsFind the secret hidden in the tree tops where you fly