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