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