Diss is a market town and electoral ward in South Norfolk, England, near the boundary with Suffolk, with a population of 7,572 in 2011. Diss raiā¦Diss is a market town and electoral ward in South Norfolk, England, near the boundary with Suffolk, with a population of 7,572 in 2011. Diss railway station is on the Great Eastern Main Line between London and Norwich. It lies in the valley of the River Waveney, round a mere covering 6 acres and up to 18 feet deep, although there is another 51 feet of mud.