A 30-metre-high geyser has erupted without warning from Lake Rotorua in New Zealand's central North Island, waking local people living near the lake edge.

The geyser of water which shot out of the lake about 4am local time was like a cap blowing off a well shaken bottle of fizzy drink, the Rotorua Lakes Council geothermal inspector Peter Brownbridge said.

Brownbridge said the geyser, while noisy and spectacular, was nothing to worry about, with the area known for its geothermal activity.

"Hydrothermal eruptions happen reasonably regularly in that area of the lake edge, but they more often than not just cause a bit of bubbling up of water and mud from the lake bottom, rather than creating a geyser."

"We don't see many bigger ones these days although eruptions like this were quite common about eight years ago."

Local resident Tawhanga Nopera who lives in Ohinemutu on the lake's edge, said she was woken by a deep rumbling sound.

"We've been in this region forever, so we're kind of used to the earth moving, things opening up, boiling water bubbling up out of the ground from cracks where it hasn't been before, but nothing like this."

Lake Rotorua formed within a large caldera volcano that erupted 240,000 years ago.