This guide will be updated frequently until everything is marked on these maps. Not everything will be notated right away as I'm not going to fill in every detail purely from memory, instead replaying the game to mark the exact locations.
So I'm replaying the game a second time and keeping track of where EVERYTHING is located as well as what ability you need to access things you find as you explore Hallownest.
Youll also find a Whispering Root tree at the top east side. While there's an ingame item that will show you the locations of all the Grubs you haven't rescued yet, it's much later in the game, and other collectibles have no item to help you find them. Howling Cliffs is a Location in Hollow Knight. With all the backtracking you'll be doing, it's very easy to forget where the A item requiring B upgrade was located.
For a game as massive as Hollow Knight, maps are essential.