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
Explore all caves
Find all missing passengers
Pass 50,000 steps
Cut down 1000 trees
Collect all robot pieces
Craft all items
Killed downed enemy with rock
In Single Player, don't kill any cannibals for more than 10 days in a row
Eat all mushroom types
Use the compass
Kill shark. Alone in Single Player or together in Multiplayer.
Sleep on yacht
Kill 6 or more fish with a stick of dynamite. Alone in Single Player or together in Multiplayer.
Set off 20 bombs
Collect all cassette tapes!
Knock down 6 or more trees with 1 explosive. Alone in Single Player or together in Multiplayer.
Kill all animal types and display heads
Play through entire game without killing or eating animals. Alone in Single Player or together in Multiplayer.
Finish Game
Craft 10 medicine items
Grow all plant types
Catch fish with a trap. Alone in Single Player or together in Multiplayer.
Eat an entire family
Build a super long wall
Repair a shelter
Chop up 50 bodies
Share a weapon in MP
Cut down 100 trees
In Single Player, kill 100 cannibals
Eat an enemy
Kill bird with arrow
Survive 5 nights
Share a food or drink item in MP
Revive one co-op player
Make and wear stealth armour
Kill a bunny. Alone in Single Player or together in Multiplayer.
Survive 1 night
Sleep with another player (group sleep)