A MYSTERY hot air balloon caused quite the stir after flying over most of Wiltshire. 

The craft, branded with the Red Bull logo, traversed the county's airspace on Monday, February 6, passing over people's homes and places of work.

It peaked many residents' curiosity as it went, and set social media abuzz.

Residents were all asking the same questions - why was it being followed by two helicopters? And what was that hanging underneath it? 

Indeed, the biggest mystery was what appeared to be an unidentifiable bowl-like structure suspended underneath the balloon's conventional basket.

Some speculated that this was a 'hot tub' or a 'swimming pool', others thought it might be a 'skate park in the sky'.

The balloon seems to be part of Red Bull UK's latest high-adrenaline, often insane, sporting stunts. 

Swindon Advertiser: The Red Bull hot air balloon carrying a mystery structure over a house in WiltshireThe Red Bull hot air balloon carrying a mystery structure over a house in Wiltshire (Image: Gale Saunders)

The energy company made several posts on its Twitter account responding to the massive public buzz caused by the balloon's presence, teasing what it might have been up to with the stunt. 

Replying to one person who shared an image of the balloon, Red Bull said: "It could be anything."

But then it added, in response to someone suggesting it might be carrying a swimming pool: "There's something way better than a swimming pool up there."

But some eagle-eyed residents with good cameras managed to get good clear photos of a BMX bike strapped to the side of the balloon's basket, leading to speculation that the structure was some sort of BMX course.

The bike's all-orange frame and bars led some people to believe that Scottish BBMX athlete Kris Kyle was involved. 

As the day progressed, the balloon passed over several areas of Wiltshire, including Swindon, but Red Bull seemed determined to keep people in the dark about what was going on. 

At one point the account tweeted: "Can confirm this is *not* a spy balloon," in reference to the Chinese weather balloon shot down in US airspace recently. 

After people started to beg for answers the account simply replied: "You’ll have to wait and see."

It ended its string of tweets by saying "Any guesses," before adding: "Well, today was a lot of fun."

Swindon Advertiser: A side-on shot of the Red Bull hot air balloon and whatever it is that was hanging underneath itA side-on shot of the Red Bull hot air balloon and whatever it is that was hanging underneath it (Image: Gale Saunders)

Gale Saunders managed to get some great snaps of the balloon as it passed over her,

"Not an everyday thing coming over the workplace near Latton," she said.