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.
Revive 10 co-op players
Pass 50,000 steps
Cut down 1000 trees
Eat an entire family
Play through entire game without killing or eating animals. 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
Eat all mushroom types
Find all missing passengers
Kill shark. Alone in Single Player or together in Multiplayer.
Collect all cassette tapes!
Explore all caves
Kill 6 or more fish with a stick of dynamite. Alone in Single Player or together in Multiplayer.
Knock down 6 or more trees with 1 explosive. Alone in Single Player or together in Multiplayer.
Grow all plant types
Kill all animal types and display heads
Craft all items
Finish Game
Collect all robot pieces
Revive one co-op player
Share a food or drink item in MP
Craft 10 medicine items
Cut down 100 trees
Sleep with another player (group sleep)
Eat an enemy
Share a weapon in MP
Repair a shelter
Build a super long wall
Killed downed enemy with rock
Chop up 50 bodies
In Single Player, kill 100 cannibals
Catch fish with a trap. Alone in Single Player or together in Multiplayer.
Make and wear stealth armour
Use the compass
Kill bird with arrow
Survive 5 nights
Kill a bunny. Alone in Single Player or together in Multiplayer.
Sleep on yacht
Survive 1 night