A teen was arrested after police were called to a "street party" which attracted around 300 people next to a London landmark.
The event reportedly featured a DJ pumping out music next to the Cutty Sark in Greenwich.
Police said a teenager had been arrested, and a dispersal order was put in place.
Frustrated social media users have criticised the event, which was held four days ahead of England's national lockdown ending.
Under current rules, people are only allowed to meet one person from another household outdoors.
Video from the scene shows young people congregating on the bank of the Thames with loud music playing.
In a statement police said: "Police were called at 3.08pm on Saturday, 28 November to reports of a large group of people in King William Walk, SE10.
"Officers attended and four approximately 300 people congregating in the area and drinking alcohol.
"Officers engaged with the group and they were made to disperse.
"An 18-year-old man was arrested on suspicion of breaching Covid regulations."
One furious Twitter user wrote: "This is #Greenwich RIGHT NOW.
"In a #pandemic I can’t shop or walk because it’s like a f****** street party of complete c***ts. Beggars belief. #covid19 #selfish."
Another posted: "Seems lockdown is over in Greenwich tonight.
"A couple hundred 16-17-18 year olds have turned up for a party, complete with a DJ."