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