Here is a 100% walkthrough of Chapter 3: Berry Mire including all the secret locations and the missable achievement
Pacifist.
Secret / Collectible #1 - 0:13
Secret / Collectible #2 - 2:13
Secret / Collectible #3 - 4:06
Secret / Collectible #4 - 6:44
Secret / Collectible #5 - 9:08
Pacifist - 1:25 to 8:05
The Pacifist achievement in Unravel worth 297 pointsMake it through the mire in one go without swatting any mosquitoes