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