About 2,000 passengers attempting to travel to London Gatwick Airport have been redirected to Cardiff after disruption caused by drones.
Ten thousand travellers were stranded at Gatwick Airport overnight after drones were seen flying over the perimeter fence.
Outgoing flights have been grounded, while inbound journeys have been diverted across the UK and Europe.
One traveller said the level of disruption was "incredible".
John Byrne, from London, was travelling back from Fuerteventura with his son Rob, daughter-in-law Jessica and their 16-month-old daughter Alice, when his flight was redirected to Cardiff Airport in the Vale of Glamorgan.
He said: "It was chaos at the airport because there were a lot of passengers, no-one knew what to do and there weren't many people around to help.
"We were just told to make our own way home and the company would reimburse us, so we're getting a bus to Cardiff, coach to Victoria and then another train home.
"Its not a great way to end the holiday, spending nine hours in all on the plane. It was pretty stressful, especially with a 16-month old child, but she was great.
"Its also a huge inconvenience, especially so close to Christmas. I've had to take another day off work which I now have to make up somehow.
"The disruption it has caused is incredible."
The Holiday Inn Express near Cardiff Airport said it was flooded with stranded passengers and all 111 rooms were booked out with late arrivals.
Victoria Rees, from Cirencester, Gloucestershire, was on a flight from Cancun, Mexico to Gatwick.
"Originally they said they had some bad news and we were going to Shannon (Cork, Ireland) but then we ended up here," she said.
"We were sat on the tarmac for two-and-a-half hours thinking Gatwick might reopen but then the pilot told us we couldn't fly anymore.
"I'm quite mellow about it but there were a lot of angry people on board. Some had kids and babies and there were some trying to get back to Scotland."
John Pugsley, 62, from Jersey, was attempting to fly home from Fuerteventura via Gatwick, but missed his connecting flight as a result of the diversion.
"Flybe don't fly from Cardiff to Jersey on Thursdays so I have to wait until tomorrow morning," he said.
"It was chaos at the arrivals hall. There were four or five flights all landing at the same time with just two members of airport staff trying to sort taxis and hotels for hundreds of people."
Four EasyJet flights were diverted to Cardiff, and the budget airline has said it will reimburse customers.
Taxi firms in the Vale of Glamorgan have also been busy as a result of the disruption.
John Lewis, who co-owns a taxi company, said: "We've been absolutely flat-out since 1am - people asking us to take them all over the country.
"Apparently passengers were told they could claim back the taxi fairs so we've had people asking us to drive them to Gatwick, Exeter, London, Worcester, the Midlands, all over.
"Unfortunately we didn't have enough cars on this morning when the calls started coming but it's been non-stop since then, mostly back and forth to Cardiff train station.
"Its been very busy and very lucrative."
Cardiff Airport CEO Debra Barber said: "It's not a regular occurrence but whenever we have any inclement weather conditions or if there are any security or other issues at other airports, Cardiff Airport obviously is one of the key airports because of our position and our capacity and our capability, then we're always one of the airports that would be at the front of these kind of operations."
Cardiff Airport officials said the situation was still "changing rapidly".
"A lot of flights are now being cancelled rather than diverted, whereas earlier we took flights that were already airborne," said a spokeswoman.
"If any requests do come in, we will decide how best to facilitate them on a case by case basis."