Manawatu Gorge

The Manawatu Gorge (in Māori Te Apiti, meaning "The Narrow Passage") runs for 6-9 km between the Ruahine and Tararua Ranges in the south part of the North Island of New Zealand, linking the Manawatu and Hawke's Bay regions. It lies to the northeast of Palmerston North. Its western end is near the small town of Ashhurst, its eastern end is close to the town of Woodville.

The Manawatu Gorge is significant because, unlike most gorges, the Manawatu River is a water gap, that is it runs directly through the surrounding ranges from one side to the other. This was caused by the ranges moving upwards at the same time as the gorge was eroded by the river, instead of the more usual erosion of an already existing range.

The Manawatu River is the only river in New Zealand that starts its journey on one side of the main divide and finishes it on the other side.

The road through the Manawatu Gorge, State Highway 3, is on the south side of the river, and was completed in 1872. It is the primary link between the two sides of the lower North Island. Other than Saddle Road and the Pahitatua Track, both narrow windy local roads a few kilometers north and south of the Manawatu Gorge, the gorge is the only east-west road connection between the Akatarawa Valley, 100 kilometres (62 mi) to the south, and SH5 between Taupo and Napier 150 kilometres (93 mi) north of the Manawatu Gorge.

The road through the Manawatu Gorge has a history of sometimes being closed by slips, especially following inclement weather.

A single track rail connection was established on the northern side of the gorge; it was completed in 1891 and is now part of the Palmerston North – Gisborne Line. The rail connection is mainly used by goods trains; there are currently no scheduled passenger rail services through the gorge. Occasional railway excursions, typically with steam trains, also make use of the scenic Manawatu Gorge Railway line with its two tunnels and several small bridges.

...
Wikipedia