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