Here is the full list of all 45 The Forest achievements. It takes around 50-60 hours to unlock all of the achievements on Windows.
Play through entire game without killing or eating animals. Alone in Single Player or together in Multiplayer.
Find all missing passengers
Pass 50,000 steps
Explore all caves
Collect all robot pieces
Collect all cassette tapes!
Finish Game
Build a super long wall
Cut down 1000 trees
Use the compass
Revive 10 co-op players
Revive one co-op player
Share a weapon in MP
Share a food or drink item in MP
Sleep with another player (group sleep)
Eat an entire family
Craft 10 medicine items
Craft all items
Eat all mushroom types
Kill all animal types and display heads
Kill 6 or more fish with a stick of dynamite. Alone in Single Player or together in Multiplayer.
In Single Player, kill 100 cannibals
Grow all plant types
Cut down 100 trees
Set off 20 bombs
Knock down 6 or more trees with 1 explosive. Alone in Single Player or together in Multiplayer.
Chop up 50 bodies
Killed downed enemy with rock
Eat an enemy
Make and wear stealth armour
In Single Player, don't kill any cannibals for more than 10 days in a row
Repair a shelter
Catch fish with a trap. Alone in Single Player or together in Multiplayer.
Kill shark. Alone in Single Player or together in Multiplayer.
Survive 5 nights
Sleep on yacht
Kill bird with arrow
Kill a bunny. Alone in Single Player or together in Multiplayer.
Survive 1 night