Floating Lamp World is a dark area accessible from the lightbulb in the Red & Blue Passage.
Features
This is world is very dark and has lot of chasers running around in it. The only way to see your surroundings is by standing underneath one of the floating lamps. This makes it rather tricky to navigate. Using the Lamppost effect illuminates your field of vision slightly. Southwest from the entrance is a mouse by one of the lamps. Interacting with it will take you to the Picnic Table.
Directions
Kubotsuki's Nexus → Nail Board → Red & Blue Passage → Floating Lamp World