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.
Explore all caves
In Single Player, kill 100 cannibals
Pass 50,000 steps
Cut down 1000 trees
Craft all items
Chop up 50 bodies
Killed downed enemy with rock
Eat an entire family
Eat an enemy
Kill all animal types and display heads
Eat all mushroom types
Catch fish with a trap. Alone in Single Player or together in Multiplayer.
Find all missing passengers
Build a super long wall
Finish Game
Craft 10 medicine items
Collect all cassette tapes!
Grow all plant types
Set off 20 bombs
Knock down 6 or more trees with 1 explosive. Alone in Single Player or together in Multiplayer.
Share a weapon in MP
Share a food or drink item in MP
Collect all robot pieces
Sleep on yacht
Kill shark. Alone in Single Player or together in Multiplayer.
Repair a shelter
Kill 6 or more fish with a stick of dynamite. Alone in Single Player or together in Multiplayer.
Kill a bunny. Alone in Single Player or together in Multiplayer.
Revive 10 co-op players
In Single Player, don't kill any cannibals for more than 10 days in a row
Kill bird with arrow
Make and wear stealth armour
Cut down 100 trees
Use the compass
Survive 5 nights
Revive one co-op player
Survive 1 night
Sleep with another player (group sleep)