Why isn’t there a tunnel connecting New Zealand’s main islands?

The havoc wrought by huge swells and gales in the deep and turbulent Cook Strait between the North and South Islands is a recurring feature of the country’s roughest weather. Breakdowns of New Zealand’s ageing ferries have also caused delays.

A tunnel or bridge crossing the approximately 25km to 30km (15 miles to 18 miles) of volatile sea is so unlikely for the same reason that regularly vexes the country’s planners – solutions for traversing New Zealand’s remote, rugged and hazard-prone terrain are logistically fraught, analysts said.

A Cook Strait tunnel would dramatically reduce the three- to four-hour sailing time between the North Island, home to 75 per cent of the population, and the South Island.