Some revellers had concerns about the safety of the venue and police were alerted at around 4am
Around 200 revellers braved the putrid conditions to access the area inside the tunnels at the mouth of the River Ouseburn in Newcastle city centre where a sound system and lighting had been rigged up.
But some revellers had concerns about the safety of the venue and police were alerted at around 4am on the morning of Sunday March 4 to break up the party.
They are now investigating the organisers.
Chief Inspector Dave Pickett 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.
The entrance to the network of underground tunnels in Newcastle
Equipment seized by police in the early hours of Sunday morning
Police are now investigating the organisers
"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."
Anyone who has any information regarding the rave should contact police on 101 quoting log 158 12/03/17 or Crimestoppers anonymously on 0800 555 111.