A while ago (around 2 years back) I decided to map all the secrets in Hollow Knight, because there are quite a lot and quite a lot that most people never know, and I was pretty sure I had enough knowledge of the game to have found practically everything (in Hollow Knight you never know absolutely everything). But mapping the Dummm rooms was boring so I got tired of it, and dropped the game for the rest of my life.
I don't have the time, or patience, to continue this project, and I also don't want to lose all my progress to a hard drive failure, so here it is. Feel free to do anything you want with it (as permitted under CC-BY-SA of course). I'd be quite happy if someone [interested] continues it since there is literally no information on the Dum rooms (really, it's kinda useless, but not everything has to be useful)
At the time of writing I was thinking on giving some interesting descriptions and stuff, and there were 2 prototypes in the stub, but I was commited to mapping everything first and then writing my thoughts.
By the way, I think one of the most interesting ones is the P5 Hitless one and the Radiance Silhouette.
Raw file (I need to learn how to properly put an iframe here): hk-secrets.txt
The Ultimate Hollow Knight Secrets Guide
Big geo ball
Throne room lore tablet
Void Tendrils room
Mantis Lords Lifeblood room
Weaver's Den
Beast's Den Wings skip
Hermit Fluke
Dream Nail
Our voices will cry out again
Shade Beast
Fog Canyon Lifeblood room travellers
Seals
Traitor Lord Arena Delicate Flower and Cloth
Lifeblood Chamber Arcane Egg
Delicate Flower Other Receivers
Hollow Knight Radiance Silhouette
King Workshop
Mushroom king
White Palace Skips
lore tablets - There are many secret lore tablets to find in Greenpath, Fungal Wastes
Mister Mushroom Riddle Tablet
Mister Mushroom Mission
Abyss Creature
Void Idol
Land of Storms
Path of Pain
Weaver's Den Secret Room
Weaver's Den Secret Room Seal of Binding
Hollow Knight Nursery
Shrine of Believers
Eternal Ordeal
Mender Bug
King Throne sitting
P5 Hitless jewel (https://youtu.be/Nz6toUZeDds?t=2995)
Relics
Colo Bugs in Crossroads Thermal Spring
Stag Egg
False Knight Mace Bug
Greenpath Supported platform to Grub
Greenpath Lifeblood Room near Hornet
Colletctor Vitruvian Grub
Teacher's Archives Bench with her face
False Knight breakable wall
Elderbug waving if you ignore him the first time
Millibelle the Thief
Leg Eater eaten by Divine
Mask Maker's mask off
Lurien' Diary
Dum rooms
Greenpath, top of cornifer and grub room, where vine is located
Greenpath, west of the Massive moss charger, top of vertical room
Crossroads, Fungal Wastes transition where you have to dash, reveals a totem
Fungal Wastes, west of dashmaster, only by walking to the left
Fungal Wastes, middle of bridge to City, jumping on a hole on the ceiling reveals a large soul totem
Soul Sanctum, in rooftop entrance just before Soul Master, gives access to Spell Twister
Crossroads, in well pit, gives Hallownest Seal
Resting Grounds, right below the breakable floor, breaking right wall
Resting Grounds, top right of right breakable wall in tomb, breaking ceiling
Resting Grounds, right of right breakable wall, breaking second breakable ceiling, gives access to grey mourner
Resting Grounds, right of right breakable wall, breaking wall right of chest, gives access to Soul Eater
Resting Grounds, walking right in tunnel before Soul Eater, gives Wanderer's Journal
Resting Grounds, breaking ceiling before Soul Eater
Resting Grounds, tomb left, breaking ceiling
Resting Grounds, tomb left, after breakable ceiling, breaking right wall
Resting Grounds, tomb left, right of auto-breakable floor, gives Hallownest Seal.
Resting Grounds, breaking wall below Xero room entrance, gives Soul Totem.
Have I said how much I love Hollow Knight already? So, here goes some secrets/things (if not all) in this game which you might not know about, ordered from least secret to impossible to find (assuming you didn't follow any guides, which you should [not have]), from someone who's played for hundreds of hours and studied almost the entire wiki.
This game has too many things to find and some of them are not too interesting to cover, so I won't cover game progress secrets (because it's hard to define what's a secret and what's not), geo rocks, most relics, and most lifeblood cocoons; you can find some of these in other places like the wiki or the interactive map.
At the end there is a section covering practically every room that makes a "Duummmm" sound effect, I'll also mark in the main secrets if they give a dum sound effect.
## Giant Geo Deposit
Or as I like to call it: Big Geo Ball. In Kingdom's Edge, below the Nailmaster's Hut there is a discrete entrance to a hut
## Lifeblood Chamber Arcane Egg
I missed this in my first playthrough, there were two holes and I chose the second, then I thought that hole could have something in it, but it was too late. In my second playthrough I remembered it and got the arcane egg
## Dum rooms
Rooms that make the "dummm" sound effect when you discover them.
Since I found no place that shows them, I'm listing them here. It's probably not 100% complete tho, because I started collecting them when i got to massive moss charger