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