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