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