Diss is a South Norfolk market town close to the Suffolk border, with its old centre gathered around Diss Mere. The lake is the thing that makes the town itself memorable: a deep, still pool beside the shops, with ducks, benches, and a sense that the town grew around water before it grew around roads.
The town works best as a quiet base for the Waveney Valley and the Norfolk-Suffolk border country. The Boudicca Way starts or ends here, and rural lanes make the area good for cycling if you are happy with maps and slow roads. Diss is also on the London-Norwich rail line, which makes it easier to reach than many East Anglian market towns.
Most of the stronger sights sit just outside town rather than on the high street. Bressingham Steam and Gardens is the family-friendly one; the 100th Bomb Group Memorial Museum gives the surrounding countryside a sharp Second World War story. Diss is not a place to rush across England for, but if you are nearby it has enough texture for a good day.