The other day I flew TZA-SPR and back in Belize, which may not be too rare, as there are several scheduled flights per day... with Cessna and BN-2 aircraft.
It was a bit disappointing though, because the original itinerary was TZA-BZE-CUK-SPR: three 5-minute segments and two 5-minute layovers, but there was no demand for the other legs apparently, and they decided to fly directly.
The first segment is between both city airports: TZA (Belize Municipal) and BZE (Belize International), only 8 miles away from each other. I wonder if any other city has scheduled flights between 2 of their airports. I could understand, for example, EWR-JFK -with a helicopter-, but Belize City has a population of only 60,000 people!