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.
Finish Game
Share a weapon in MP
Collect all robot pieces
Set off 20 bombs
Kill 6 or more fish with a stick of dynamite. Alone in Single Player or together in Multiplayer.
Kill shark. Alone in Single Player or together in Multiplayer.
Knock down 6 or more trees with 1 explosive. Alone in Single Player or together in Multiplayer.
Kill all animal types and display heads
Repair a shelter
Craft 10 medicine items
Eat all mushroom types
Killed downed enemy with rock
Kill bird with arrow
Kill a bunny. Alone in Single Player or together in Multiplayer.
Collect all cassette tapes!
Chop up 50 bodies
Grow all plant types
Sleep on yacht
Cut down 100 trees
Revive 10 co-op players
Make and wear stealth armour
Use the compass
Share a food or drink item in MP
Survive 5 nights
Eat an enemy
Revive one co-op player
Survive 1 night
Sleep with another player (group sleep)
Eat an entire family
Craft all items
Play through entire game without killing or eating animals. Alone in Single Player or together in Multiplayer.
Explore all caves
Build a super long wall
In Single Player, kill 100 cannibals
Find all missing passengers
Pass 50,000 steps
Cut down 1000 trees
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.