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