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 10 medicine items
Revive 10 co-op players
Finish Game
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.
Use the compass
Share a food or drink item in MP
Set off 20 bombs
Revive one co-op player
In Single Player, kill 100 cannibals
Sleep with another player (group sleep)
Make and wear stealth armour
Cut down 100 trees
Eat an entire family
Chop up 50 bodies
Eat an enemy
Kill bird with arrow
Grow all plant types
Survive 5 nights
Sleep on yacht
Survive 1 night
Kill a bunny. Alone in Single Player or together in Multiplayer.
Share a weapon in MP
Craft all items
Kill all animal types and display heads
Play through entire game without killing or eating animals. Alone in Single Player or together in Multiplayer.
Explore all caves
Killed downed enemy with rock
Build a super long wall
Find all missing passengers
Kill shark. Alone in Single Player or together in Multiplayer.
Collect all cassette tapes!
Eat all mushroom types
Pass 50,000 steps
Repair a shelter
Collect all robot pieces
Cut down 1000 trees
Knock down 6 or more trees with 1 explosive. Alone in Single Player or together in Multiplayer.
Catch fish with a trap. Alone in Single Player or together in Multiplayer.