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