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
Find all missing passengers
Collect all robot pieces
Cut down 1000 trees
Repair a shelter
Pass 50,000 steps
Grow all plant types
Killed downed enemy with rock
Catch fish with a trap. Alone in Single Player or together in Multiplayer.
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 shark. Alone in Single Player or together in Multiplayer.
Eat all mushroom types
Build a super long wall
Kill all animal types and display heads
Finish Game
Craft 10 medicine items
Sleep on yacht
Knock down 6 or more trees with 1 explosive. Alone in Single Player or together in Multiplayer.
Craft all items
Collect all cassette tapes!
In Single Player, kill 100 cannibals
Eat an entire family
Set off 20 bombs
Chop up 50 bodies
Revive 10 co-op players
Kill a bunny. Alone in Single Player or together in Multiplayer.
Share a weapon in MP
Share a food or drink item in MP
Use the compass
Survive 5 nights
Kill bird with arrow
Make and wear stealth armour
Cut down 100 trees
Revive one co-op player
Eat an enemy
Survive 1 night
Sleep with another player (group sleep)