Surfers visiting Sydney's world famous Bondi Beach on Tuesday November 26th, were in for a little shock - The normally crystal clear blue ocean waters had turned a crimson red! However, before you get all concerned, it was not the result of a brutal shark attack, nor oily tomato sauce as was the original rumor! Instead the culprit is an over abundance of an algae called noctiluca scintillans or sea sparkle.

Known to happen frequently in the oceans around California, the phenomenon called Red Tides occurs when these microscopic organisms become concentrated in small sections of the ocean. Australian authorities believe that this latest increase in population can be attributed to a recent upswell that brought in nutrient-rich waters to the coastline.

The good news is that it does not last for long periods of time - In fact, Bondi Beach, which was closed by the authorities on Tuesday, is already open to visitors and sporting its usual blue color. And though many people are afraid of the intense redness, besides causing a slight irritation to the skin and eyes, the algae are not harmful to humans.

However, as the microorganisms die and sink in the shallow waters of the coastline, they decompose and cause areas of low oxygen. If the depletion is severe, as seems to be the case here, it does kill marine animals that reside in these zones.

The best part about the Red Tides is that while they may appear a little intimidating during the day, at night the organisms become bioluminescent thanks to a chemical reaction caused when they jostle against each other in the ocean waves. The result? Magical looking electrifying blue flashes in the normally dark oceans. In California, surfers even use this natural phenomenon as an excuse to hit the waves at night!

However, the beachgoers in Sydney that have very rarely encountered this do not seem to be as adventurous. Though people have been visiting the beaches in droves very few, have dared to tread in. Also, the authorities have been closing affected beaches until the color disappears, which hopefully will be soon, given that the weekend is expected to be a scorcher!

Resources: Huffingtonpost.com, dailymail.co.uk, news,yahoo.com