On his first dive with his new GoPro camera, diver Ryan Belworthy found more than just fish on the reef off Mount Maunganui's Rabbit Island after unearthing what looks like a large piece of carpet.

The Bay of Plenty snorkeler estimates the swath of carpet festooned over the reef is at least three metres by three metres in size, and has no idea how it got there.

Diver Ryan Belworthy filmed the footage near Rabbit Island.

'It's massive,” says Ryan. 'I've done three or four dives there but I've never noticed it previously.

'And it didn't have any mussels on it or anything growing on it, so it did look pretty fresh.

'It looked like it was in mint condition.”

After posting the video footage (below) on a number of forums, several comments have suggested that it may be part of the former Tay Street surf reef that was simply left behind by contractors.

But the real answers regarding its place of origin remain remain a mystery, for now.

The artificial surf reef was sited 250m off the beach at Tay Street, less than two kilometres from where Ryan found the mysterious carpet.

The current generally sets east-west along the beach.

The artificial reef, which comprised of large bags full of sand on the sea floor, was meant to promote good riding waves, but failed to work as originally promoted.

The $1.5 million reef was built by the Mount Maunganui Reef Trust from 2005 to 2008 via donations from the public and community funding groups.

Designed by Raglan-based company ASR, the sandbag structure has also been sold around the world, including Britain, where there are also known problems with the concept.

Local lifesavers said it caused rips, holes and scouring in a popular section of beach. The giant sand bags were eventually cut open and lifted out in an $87,000 contract awarded to Underwater Solutions last spring.

The mystery of the ‘reef carpet', however, will be solved on Monday when Regional council contractors attempt to retrieve it and offer an opinion on its origin after it has been salvaged.