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