More than 40 colorful hot air balloons filled the skies above Bristol for the city's annual fiesta—with the event kept top secret to prevent crowds from gathering.

Bristol Balloon Fiesta is the largest annual hot air balloon event in Europe and normally attracts more than 500,000 visitors.

Organizers were forced to cancel the usual on-the-ground activities at the Ashton Court estate due to social distancing rules.

They kept Monday's mass ascent, which involved 43 balloons, under wraps until it had started to prevent people from gathering at the site.

It had previously been announced that the fiesta, which is in its 42nd year, would only take place as a “flypast" in the sky.

There will also be a virtual “nightglow", when tethered balloons light their burners in time to music.

A hot air balloon flies over South Bristol (Ben Birchall/PA)PA Wire/PA Images - Ben Birchall

Chris Allcock, chairman of the Bristol International Balloon Fiesta, said:

“We're all deeply saddened that we can't gather at Ashton Court to celebrate the 42nd Bristol International Balloon Fiesta."

“We have been working with our balloonists and the authorities to create an event which adheres to the social distancing restrictions."

“We are inviting Bristolians to watch the balloons from the safety of their own doorsteps and gardens."

“Social distancing means we absolutely cannot gather in parks or Bristol's open spaces or invite our audiences to see the balloons take off or land, to protect our pilots and the public."

“Instead we're asking people to give them a wave as they fly past Bristol's communities."

People shared their photos of the flypast on social media.

Despite the continuing pandemic, it was a lovely day.