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