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