SINGAPORE – A black smoke ring that appeared in the sky over Sentosa on Sunday was caused by routine testing for one of the island destination’s attractions, its spokesman said.

The smoke ring hovered over the Tanjong Beach, with many in the area curious as to what the phenomenon was.

Marketing associate Nuruddin Selamat was one of them. The 31-year-old filmed the bizarre sight before posting it on video sharing platform TikTok.

In his video, playfully captioned “errmmm, should we start running?”, a huge black smoke ring can be seen floating over palm trees on the beach. The clip has been viewed more than 17,000 times.

Contacted, the Mount Faber Leisure Group spokesman said that the black smoke ring was caused by routine testing of flame generators from Sentosa’s Wings of Time show.

The show - which combines laser, fire and water effects to a soundtrack - runs twice nightly and is located near the Beach Station, about 1.4km away from the Tanjong Beach.

He added: “We would like to assure the public that all safety procedures are adhered to while performing the routine checks.”

Mr Nuruddin, who was having a drink and some snacks with his friends when he spotted the smoke ring, said: “Honestly, we were super confused, and we thought it was a swarm of bees.

“I was actually thinking if I should run, but I decided to take a video first because no one would believe me if I did not have evidence.”

He added that the other beachgoers around him were also curious, and many followed it as it drifted.

Mr Nuruddin said that the smokey oddity moved very slowly, and appeared to fade away after a few minutes.

Weather and climate scientist Koh Tieh Yong said that the smoke ring is not a weather phenomenon, but a vortex ring formed by a pulse of hot air shooting upward into a stable atmosphere.

Dr Koh said: “The vortex ring forms at the leading circular edge of the rising plume, and as it rises, the ring expands because the surrounding air is entrained into it.”

He added: “We see the vortex ring, probably because smoke particles were injected into it from the moment the plume was shot and then were trapped inside since.

“The smoke concentration dilutes as the ring expands, and we see the ring grow faint. Eventually, the vortex ring dissipates when stronger winds at higher levels disrupt the organised rising motion of the plume.”

Previously, similar smoke rings were spotted in Sentosa in 2022 and 2017, according to local media reports.

At the time, it was reported to most likely be smoke caused by fireworks testing for Sentosa’s Wings of Time pyrotechnics show.

Mysterious smoke rings have also been seen in other countries in recent years. 

In March, one was spotted in Moscow, and Mr Anton Gerashchenko, advisor to the minister of internal affairs of Ukraine, shared a clip of it on social media platform Twitter.