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