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