Invercargill and Dunedin have been closed by floods once a decade or so. Graeme 1.1.1 Large parts of Dunedin are below mean sea level, some around a metre. Invercargill is just above, but close enough that a flood combined with a high tide makes things pretty wet. Both suffer from being built on very weak ground, especially Invercargill, so both are never going to be more than they are now and unlikely to get much future investment. It's not only airports that are at risk from sea level rise. The State Highway and railway going past Dunedin Airport are only slightly higher and just as at risk in many other places.