Three illegal raves were stopped by police in Bedfordshire over the bank holiday weekend.
At Westoning officers found more than 150 people at 0130 BST on Sunday and turned away more than 400.
Two hours later they stepped in to stop a second at Thorn turn, near Dunstable, where 100 people had gathered with 30 to 40 vehicles.
Earlier in the morning police had stopped a smaller rave at the Blue Lagoon in Arlesey.
Quality of life
At the biggest rave at Westoning, police found two huge sound systems - one system stacked to the height of a double-decker bus.
Deputy Divisional Commander Supt Andy Martin, based at Dunstable Police Station, urged residents to contact them with any intelligence on raves, stressing early intervention was the key to stopping events.
"If these events had not been disrupted there is no doubt that they would have had a detrimental impact upon the quality of life of local residents throughout the bank holiday weekend."