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