Blue Room
Items in this room:
Gold Coins: 1 | Keys: 0 | Potions: 1 | Gems: 0
The room does not appear to be very blue. But don't worry, this area will live up to its name shortly. Make your way out of the minecart (very tricky to do by just walking, so Dash out to make your life easier) and toward the giant door in the distance. Shoot the large skull on the door once to cause blue flames to appear in the eye sockets, then shoot the forehead a second time to open the door. In the PCVR version, there's no skull. You can use Odin vision to spot a hidden Runic Plate. Shoot that once to reveal it, and a second time to open the door.
The opened door is very enticing, but don't enter quite yet. Once you get close to it, look to the left to find a crate that can be destroyed for Gold Coins. Looking to the right of the door in Odin Vision will show a hidden chest. Shoot it open for a Purple Potion. Now move through the door into an actual blue room.
The door will close behind you, leaving you trapped. Enter Odin Vision to spot four circle-highlighted areas within the room. Stand in each one and look at the floating objects to see a rune. Each rune will need to be entered into the Runic Door leading out of here. If you're stuck, the answer is: 
Once the correct runes are entered, the door will open. Head through into the next room.
