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 rain.

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

New Zealand Sinkhole
The massive hole is the depth of a six-storey building (Newshub/AP)

He said the area often develops 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 has seen before.

He said an underground cavity would have developed over decades.

New Zealand Sinkhole
The huge sinkhole on a farm near Rotorua on New Zealand’s North Island opened up after days of heavy rain (Newshub/AP)

Mr Tremain is planning to install a fence so livestock do not fall into the sinkhole.