SINGAPORE - A large column of water was spotted off Singapore's East Coast on Saturday (Aug 6), prompting people across the island to share photos and videos of it on social media.

It is likely a waterspout, which occurs when a type of cloud, cumuliform, forms during thunderstorms, creating low-pressure pockets.

They are common in tropical waters, and are usually spotted off Singapore once or twice a year. One was spotted in Clementi in October 2014, and reports of waterspouts have appeared in local newspapers as far back as 1908.

Waterspouts have an average diameter of 50m and has average wind speeds of up to 150kmh, the National Environment Agency said in 2007.

The phenomena can pose a threat to small boats in the water, but usually weaken and vanish when they come nearer to shore.

Saturday's occurrence led to a slew of tweets from about 4pm.

Marine Crescent resident Kenneth Ang said that it was the first time he had seen a waterspout.

"Just pray that it didn't hurt anyone," he said.

Mr Heng Xun Zheng, who saw it from East Coast, said that it was the first time he had seen such a big one.

ST reader Sonal Chopra Jaggi saw the water spout from her home at Costa del Sol condominium in East Coast. She said she "knew it was pretty harmless" and "just made for a fantastic photo op".