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