Hundreds of party-goers waded through filthy water to access a suspected illegal rave in a “dangerous” sewer, until police arrived and shut it down.
About 200 revellers were said to have risked their lives by partying in tunnels beneath bridges at the mouth of the River Ouseburn, in Newcastle, on Saturday.
But after police saw the event was publicised on Facebook, officers attended the smelly site and broke up the party at about 4am.
A number of people at the party contacted police with concerns about their safety at the rave, officers say.
No one has been arrested in connection to the event but police said the venue was “dangerous” and that organisers had put peoples’ lives at risk.
An investigation into those responsible for organising the event, which saw people meet at a nearby pub before wading through sewage water, has been launched.
Chief Inspector Dave Pickett, of Central Area Command, said: "You can clearly see from the pictures that this is a dangerous site for members of the public, nevermind an appropriate party venue.
"These events are not licensed or supported by the responsible authorities who duty is to oversee the safety of the public.
"It is not an area that is easy to access so if anyone needed the assistance of the emergency services then they would have been in severe trouble.
"We are very lucky that we are not talking about a more serious incident, particularly when you consider that many of those involved were under the influence of alcohol."
Police believe many of those involved were university students.
Anyone who was at the rave, or has any information about who organised it, should contact police on 101 quoting log 158 12/03/17 or Crimestoppers anonymously on 0800 555 111.