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