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
Repair a shelter
Explore all caves
Craft all items
Kill all animal types and display heads
Eat all mushroom types
Collect all cassette tapes!
Collect all robot pieces
Find all missing passengers
Craft 10 medicine items
In Single Player, don't kill any cannibals for more than 10 days in a row
Kill shark. Alone in Single Player or together in Multiplayer.
Build a super long wall
Catch fish with a trap. Alone in Single Player or together in Multiplayer.
Killed downed enemy with rock
Play through entire game without killing or eating animals. Alone in Single Player or together in Multiplayer.
Finish Game
Grow all plant types
Set off 20 bombs
Kill 6 or more fish with a stick of dynamite. Alone in Single Player or together in Multiplayer.
Make and wear stealth armour
Cut down 1000 trees
Eat an entire family
Share a weapon in MP
Knock down 6 or more trees with 1 explosive. Alone in Single Player or together in Multiplayer.
Share a food or drink item in MP
Kill bird with arrow
In Single Player, kill 100 cannibals
Use the compass
Chop up 50 bodies
Kill a bunny. Alone in Single Player or together in Multiplayer.
Revive 10 co-op players
Survive 5 nights
Sleep on yacht
Revive one co-op player
Eat an enemy
Cut down 100 trees
Survive 1 night
Sleep with another player (group sleep)