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