People visiting Southern Australia may be in for a surprise as mysterious foam and dead fish are washing ashore.

A microalgal bloom created by unusual weather conditions resulted in the foam spanning over hundreds of yards of coastline, the Associated Press (AP) reported.

The bloom may cause algae to grow out of control, “producing toxins that can kill fish, mammals and birds,” according to the National Oceanic and Atmospheric Administration (NOAA).

FLORIDA BEACHGOERS REPORT MYSTERIOUS STICKY SUBSTANCE WASHING ASHORE

The substance may also cause human illness or even death in extreme cases, the NOAA says.

Surfers and visitors have reported feeling sick after leaving the beach.

For more Lifestyle articles, visit foxnews.com/lifestyle

“While we were out there, we started coughing,” local surfer Anthony Rowland told the AP.

“Lots of people reached out – so many people have said [they’ve] had exactly the same symptoms,” Rowland added.

CLICK HERE TO SIGN UP FOR OUR LIFESTYLE NEWSLETTER

The foam is a byproduct of toxic organisms’ decay with marine scientists collecting samples looking to identify the organism, reported the AP.

The severity of the blooms depends on factors such as the structure of the coast, runoff, oceanography, and other organisms in the water, according to the NOAA.

CLICK HERE TO GET THE FOX NEWS APP

The South Australian beaches, Waitpinga Beach and Parsons Beach, have been closed until further notice. 

The Associated Press contributed to this report.