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