Is it a taniwha? Strange bubbles filmed in Waikato River by local

A Ngaruawahia resident has captured remarkable footage of an unexplained water eruption at the Waikato River.

Ngaruawahia local Martin Smith captured this footage of a large amount of bubbles coming from beneath the surface of the Waikato River – what could it be? Source: 1 NEWS

Martin Smith posted the video to Facebook yesterday afternoon, asking followers to help distinguish the mystery behind the bubbles.

"WTF is this?" he wrote in his caption.

"I have been living in Ngaruawahia for over 8 years and spent a lot of time at the point bow fishing but have never seen anything like this before."

Mr Smith can be heard in the video saying the river had been bubbling since yesterday morning. 

Facebook users replied with a variety of possible reasons, ranging from "methane bubbles" to the elusive "taniwha". 

The video has been shared more than 2,000 times since it was uploaded and viewed almost 100,000 times.