seaham postcode nswst Home ›› Postcode Finder ›› NSWST ›› Seaham Seaham local listingsThe suburb of Seaham is located in NSW and has a postcode of 2324. Free seaham business listing! 1Seaham Public School4c Still St 02 49886234 View more business listings in seaham Search and find other Postcodes in New South Wales or widen the search to Postcodes in Australia.