Robbie's periscope is a device used by Robbie Rotten to spy on the inhabitants of LazyTown.
It is apparently capable of spying on them without getting noticed, despite the spying end being bright blue, almost a meter high and having big eyes on it. However, there have been cases where the periscope has been discovered, and the reaction of the other characters differs between confusion at what it is, as with Sportacus
in Zap It!
, and using it to talk with Robbie directly, as Stephanie
does in LazyTown's Greatest Hits
The top of the periscope is also able to pop up seemingly anywhere around the town, despite the other end being stationary in his underground lair outside of town.
Sportacus Discovers Robbie's Periscope
Stephanie Talks to Robbie Through the Periscope