Police launched “dawn raids” on caravans and campsites on Thursday, ordering tourists to go home and stop flouting lockdown rules.
As crowds continued to flock to beaches and parks, councils and tourism chiefs warned visitors they were putting others in danger and creating “absolute chaos”.
Officers in Newquay took action after large groups spent the evening drinking and partying.
"We identified some visitors that had travelled to Newquay and stayed overnight against Public Health England advice and legislation,” they wrote on Twitter just after 6am.
"With engagement, explanation and education they moved on.”
Cornwall residents expressed anger that some visitors to the Lizard had set up tents and stayed overnight in vans at various spots, including the National Trust car park, with "blatant disregard" to public safety.
With the good weather forecast to continue throughout the bank holiday weekend, one council chief said he was “pulling his hair out” as he acknowledged there was very little they could do to deter the crowds from descending.
In Brighton, marshals will be stationed at the busiest point on the beach to disperse large groups for “public safety”.
A Brighton and Hove Council spokeswoman said they were “extremely concerned” about the lack of social distancing on the beach, with everyone congregating in one central area, and admitted that the eased lockdown rules posed “a challenge”.
“The bars are open for takeaway but there are no public lavatories open, which creates its own problems,” she said.
“This weekend, we will be encouraging visitors to spread out and make use of the long stretches of beach available.”
Locals in Brighton also complained that scores of camper vans and caravans had been parked up overnight, many containing families with children, despite clear rules stating that only day trips are allowed.
Several coastal areas have issued urgent warnings about the lack of lifeguards on duty this weekend.
The danger was illustrated when two young children on body boards were swept out to sea in St Ives on Wednesday and had to be rescued by an off-duty lifeguard who happened to be sitting on the beach.
Authorities from Skegness to Somerset pleaded with day trippers to stay away, noting that they simply could not guarantee their safety.
Sefton Council designed a spoof postcard to deter people from flocking to Merseyside's beaches this weekend, launching a campaign with the slogan: "Wish you weren't here!"
Matt Dent, a Labour councillor in Southend, warned of a second Covid-19 wave if such behaviour continued.
"It isn't Southend residents, it's people travelling from outside the borough - as far away as Manchester, from what I've heard - who seem to think lockdown is lifted, and Covid-19 is no longer a threat,” he said.
"It is a small minority who are acting in this foolish and irresponsible manner."
Andrea Davis, a Devon county councillor, said Woolacombe had been “inundated” with visitors, causing “absolute chaos”.
At the Downing Street press conference on Thursday, Matt Hancock, the Health Secretary, said those flouting social distancing risked taking the UK back to "square one".