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