Dance festival Creamfields has been cancelled on its final day after heavy rain flooded the site.
Organisers of the three-day event in Daresbury, Cheshire, said downpours overnight had left many areas unusable.
People with day tickets for Sunday had been advised not to travel to the festival earlier in the day, after all entrances were closed.
Police also urged people already there to make arrangements to leave.
Creamfields organisers said they had decided to close for health and safety reasons.
'Safety top priority'
Tens of thousands of people attended the festival and thousands more were expected to arrive for the final day.
Organisers said in a statement: "Every effort has been made to continue with the event and following an evaluation of the site the decision has been made by the promoters, Cheshire Police and multi-agencies on site to close today's final day in the interest of health and safety.
"It is our primary concern at this time that assistance is given to those on site and ensure those campers exit safely."
Cheshire Police said there was localised flooding on site and on roads around the A56 in Daresbury.
People travelling to the site to collect friends and family were being urged to use the North entrance, which is signposted off the A56.
Police said extra free shuttle buses were being made available from the site to railway stations in Warrington, Runcorn, Manchester and Liverpool.
Ch Insp Bev Raistrick said: "Our priority at this time is to ensure that assistance is given to those on the site and to ensure that anyone who has camped overnight can leave safely and via the most appropriate routes.
"Public safety remains the top priority - it is vital that festival goers assist by following all instructions and directions by police and stewards.
"Extensive planning between Cheshire Police, the two local authorities, other agencies and the Creamfields management team has taken place over the past year and contingency plans have been developed to ensure we are able to deal effectively and efficiently with every eventuality."
Deadmau5, Tiesto and Groove Armada were among the acts due to play on the last day of the three-day event.
Dutch DJ and record producer Tiesto tweeted: "I hope everyone gets home safe! Really sad cause @Creamfields is always one of the highlights of the year to play at..."
'Battered it down'
Alexandra Olczak, who is at Creamfields celebrating her friend's 19th birthday, told the BBC conditions were "not that bad".
"It's nothing out of the ordinary for a festival," she said.
"I'm in the hospitality tent so I paid a bit more for a more luxury campsite, but I visited my friends in the standard area and it's really not that bad.
"We don't really know what's going on though - the officials seem to be getting their information from Twitter.
"The sky is blue, a few tents are muddy and people are walking around.
"It's nothing out of the ordinary for a festival."
Another festival-goer, Matthew Hawes, from Brighouse, West Yorkshire, said the site was covered in puddles.
"On Friday night it started to rain and everywhere got really muddy," he said.
"Luckily the rain stopped and Saturday was pretty sunny.
"But then last night it battered it down with rain. We got no sleep and there were puddles everywhere.
"The tents were ruined so we had to leave them there rather than digging them out of the mud. Everyone was leaving stuff there."