Six-storey deep sinkhole opens on NZ farm

A farm worker has stumbled on a giant sinkhole in New Zealand.

The sinkhole on a farm in Rotorua, New Zealand. Source: AAP

A spectacular sinkhole the length of two football fields and the depth of a six-storey building has opened up on a New Zealand farm.

A worker stumbled upon the chasm before dawn this week when he was rounding up cows for milking on the farm near the North Island town of Rotorua. It appeared after several days of heavy rainfall.

The sinkhole is the length of two football fields and the depth of a six-story building. Source: AAP

Farm manager Colin Tremain told Newshub television he didn't realise just how big the hole was until he saw it in the daylight.

He said the area often developed sinkholes due to degrading limestone rock beneath the ground's surface.

GNS Science volcanologist Brad Scott told Newshub the sinkhole was three times larger than any he'd seen before.

A worker stumbled upon the chasm when he was rounding up cows for milking. Source: AAP

He said an underground cavity would have developed over decades.

Mr Tremain said he's planning to install a fence so livestock don't fall into the sinkhole.