Explained: What’s really causing ‘lines’ to appear in ocean off the Gold Coast

Residents and tourists were left scratching their heads after lines appeared in ocean off the Coast - one even described it as the Surfers Paradise ‘Loch Ness monster or Yowie’.

An ocean expert has explained why “lines” have appeared in the ocean off the Gold Coast in recent days in the wake of “Loch Ness Monster” speculation.

Residents and tourists were left scratching their heads after the lines appeared, with one even describing it as the “Surfers Paradise Loch Ness monster or Yowie”.

The ocean off Surfers Paradise. Picture: Matt Watrich

Surfers local Matt Watrach sparked a lively online debate after he posted pictures of the light-coloured streaks to a Facebook community group.

“I didn’t know what it was. I was inquisitive,” he told the Bulletin.

“Everyone had a theory - I reckon it was algae.”

The ocean off Surfers Paradise. Picture: Matt Watrich

Some suggested the lines could be shark nets, boat trails, coral spawning, a sandbank or rubbish.

Others took a lighter approach - jokingly referring to the lines as “Chinese submarines”, a “Russian gas pipe” and even a “tsunami”.

“Some of the comments were stupid, but others were a bit more realistic,” Mr Watrich said.

Bond University Associate Professor of environmental science Daryl McPhee explained the lines formed when ocean currents and river discharge mixed together.

Daryl McPhee of Bond University

“It is caused by the boundaries of two water masses, where water is a different temperature and salinity,” Dr McPhee said.

He said the lines were not harmful and usually formed after rainfall.