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.
Killed downed enemy with rock
Catch fish with a trap. 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
Kill all animal types and display heads
Eat all mushroom types
Craft all items
Find all missing passengers
Build a super long wall
Pass 50,000 steps
Explore all caves
Kill 6 or more fish with a stick of dynamite. Alone in Single Player or together in Multiplayer.
Cut down 1000 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
Finish Game
Grow all plant types
Collect all robot pieces
Eat an enemy
Set off 20 bombs
In Single Player, kill 100 cannibals
Collect all cassette tapes!
Craft 10 medicine items
In Single Player, don't kill any cannibals for more than 10 days in a row
Kill bird with arrow
Share a food or drink item in MP
Use the compass
Share a weapon in MP
Make and wear stealth armour
Repair a shelter
Cut down 100 trees
Kill a bunny. Alone in Single Player or together in Multiplayer.
Survive 5 nights
Revive one co-op player
Survive 1 night
Sleep on yacht
Sleep with another player (group sleep)