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