The Met Police said officers were called to Volt Avenue in North Acton shortly after 11pm on Saturday, having received reports of a large gathering on a moored boat.
The group was dispersed and a total of 72 people were reported for the consideration of an £800 fixed penalty notice.
The organiser, meanwhile, faces a £10,000 fixed penalty notice.
Detective Chief Inspector Thomas Bowen, of West Area, said: "This was a blatant breach of the coronavirus rules that are in place to save lives and protect the huge pressure on the NHS.
"All the people who attended this event, which appears to have been organised on social media, have quite rightly been reported for the consideration of fines.
"The Met will continue to shut down and disperse events such as this, which risk spreading a virus that has already claimed the lives of more than 100,000 people in this country."
Earlier this month, Home Secretary Priti Patel announced a new £800 fine that would be issued to anyone flouting coronavirus regulations by attending illegal gatherings of more than 15 people.
Addressing the nation at a Downing Street coronavirus briefing, Patel said: "Next week we will be introducing a new £800 fine for those attending house parties, which will double for each repeat offence up to a maximum level of £6,400.
"These fines will apply to those who attend illegal gatherings of more than 15 people in homes."
Patel said that the 'sacrifices that millions' were making are 'starting to make a difference', but that there is 'still a small minority who refuse to do the right thing'.
She continued: "The science is clear. Such irresponsible behaviour poses a significant threat to public health, not only to those in attendance, but also to our wonderful police officers who attend these events to shut them down.
"From the outset we have given police the necessary powers to enforce the rules, which are in place to stop the spread of this virus, and as these latest measures will demonstrate, we will not stand by while a small number of individuals put others at risk."Featured Image Credit: Google Maps