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.
Craft all items
Explore all caves
Find all missing passengers
Pass 50,000 steps
Eat all mushroom types
Collect all robot pieces
Play through entire game without killing or eating animals. Alone in Single Player or together in Multiplayer.
Cut down 1000 trees
Kill shark. Alone in Single Player or together in Multiplayer.
Kill all animal types and display heads
Collect all cassette tapes!
Revive 10 co-op players
Cut down 100 trees
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
Catch fish with a trap. Alone in Single Player or together in Multiplayer.
Set off 20 bombs
Kill 6 or more fish with a stick of dynamite. Alone in Single Player or together in Multiplayer.
Craft 10 medicine items
Killed downed enemy with rock
Share a weapon in MP
Share a food or drink item in MP
Repair a shelter
Sleep on yacht
Build a super long wall
Finish Game
Grow all plant types
In Single Player, kill 100 cannibals
In Single Player, don't kill any cannibals for more than 10 days in a row
Use the compass
Revive one co-op player
Eat an enemy
Survive 5 nights
Kill bird with arrow
Kill a bunny. Alone in Single Player or together in Multiplayer.
Make and wear stealth armour
Sleep with another player (group sleep)
Survive 1 night