There are no towns in NZ with a population bigger than 50,000 (the definition of a city in NZ) the largest town beginning with S is Stoke in Wellington, population around 15,000.
Sofia in Bulgaria
Sydney
takahe
San Diego
The capital of Norway is Oslo. It does not begin with S.
The most easterly city in NZ is Gisborne in the north island with a population of 33,000.
Whangarei is the biggest city in Northland, NZ.
Christchurch
Christchurch
Christchurch
Hamilton
Auckland