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.
Pass 50,000 steps
Craft all items
Cut down 1000 trees
Repair a shelter
Catch fish with a trap. 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.
Eat all mushroom types
Kill all animal types and display heads
Kill shark. Alone in Single Player or together in Multiplayer.
Grow all plant types
Revive 10 co-op players
Build a super long wall
Finish Game
Find all missing passengers
Knock down 6 or more trees with 1 explosive. Alone in Single Player or together in Multiplayer.
Killed downed enemy with rock
Craft 10 medicine items
Eat an entire family
Share a weapon in MP
Collect all cassette tapes!
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
Explore all caves
Collect all robot pieces
Set off 20 bombs
Chop up 50 bodies
Kill bird with arrow
Make and wear stealth armour
Eat an enemy
In Single Player, kill 100 cannibals
Cut down 100 trees
Revive one co-op player
Sleep on yacht
Share a food or drink item in MP
Survive 5 nights
Survive 1 night
Kill a bunny. Alone in Single Player or together in Multiplayer.
Sleep with another player (group sleep)