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