A spokesman for the force said officers moved quickly to disperse around 200 people from Stanmer Park in Brighton after receiving a call from a member of the public.
The alarm was raised at 2.30am this morning (October 25), police said, after an unusual number of people were seen converging on the area.
Sound equipment was seized from the park as the illegal ravers were removed.
Police are trying to identify the organisers of the event, who face a £10,000 fine.
Sergeant Karen Osborn said: "The earlier that we hear about raves occurring, the more likely it is that we are able to act quickly to nip them in the bud. Raves are spontaneous by their very nature and once established, especially during the hours of darkness, they are very difficult to close down safely. However, they are unlicensed and there are no controls over health and safety or facilities to ensure the welfare of those attending.
"On top of that, with the country in the grip of a worldwide pandemic, such gatherings take no account of social distancing measures, are illegal and completely irresponsible."
The earlier that Sussex Police is alerted to a rave taking place, the greater the chance of preventing them becoming established, disrupting them and dispersing those responsible for their organisation. Things people should look out for are:
- the removal of locks from secured access points
- vehicles, particularly panel vans or larger, driving off road
- groups of vehicles congregating in rural areas
- convoys of vehicles
- loud music from remote locations
Sgt Osborn continued: "While rave organisers and those who attend see no harm in their unlicensed and illegal activities, these events can cause an immense amount of disruption to communities, especially rural ones.
"On this occasion, thanks to the vigilance of the local community, we were able to shut down and clear the site within an hour, seizing a generator and a significant amount of sound equipment."
Anyone with information about the organisation of the rave is asked to report online or call 101 quoting serial 157 of 25/10.