Hollow Knight Silksong isn't one of those games that will hold your hand from the beginning to the end, which means sometimes, you'll have to figure stuff out on your own.
How to unlock the door in Craw Lake?
After you beat the mobs, the game will spawn a balloon, which you'll have to use to get to the locking mechanism above, which unlocks the door. Basically, what you need to do is jump above the balloon and strike down on it to get a little aerial boost. To strike down the balloon, hold the stick/arrow/key down and press the attack button.
Check out the gif below to see how to pull this one off.
And that's pretty much it. From there, it's a smooth ride until you get to the next puzzle.
As soon as you're out of the building, you'll notice more balloons have spawned outside, which you can use to get to new locations. Just watch out for those pesky birds.





















