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