Increased police patrols over the weekend did little to prevent crowds gathering at beauty spots in breach of Covid-19 regulations.
This followed reports of dozens of people congregating at resorts including Newcastle and Bangor last Thursday and Friday.
And images of Warrenpoint Pier showed hundreds of young people socialising there on Thursday, with nearby roads lined with cars.
Yesterday afternoon, police in Newry, Mourne and Down posted on social media that they had encountered a large number of people along the Head Road in Kilkeel "reducing everyone's ability to maintain a safe social distance".
"The vehicles parked along the road also pose a risk, especially at junctions," they wrote.
Police said numerous traffic penalty tickets had been issued.
Councillor for the area, Glyn Hanna, told the Belfast Telegraph the scenes in the Mournes yesterday were "horrendous", with massive crowds flocking into the scenic south Down area, which includes Newcastle, Murlough Bay and Spelga.
The DUP man said the narrow roads into the mountains had been so crammed with cars that farmers had not been able to get to their fields to work.
"They're going mad," he said. "The situation is horrendous.
"Stormont needs to wake up. They need to get their message right," the councillor said.
And closed public toilets made things worse, he feared.
"The toilets are not open. That means there's nowhere for people to 'go' - so they're using the lanes and hedges - men and women alike," he continued.
"People are travelling 30 or 40 miles to get to south Down.
"It's not that we don't want people to visit south Down - it's that we are in no position to welcome them at the moment," he added.
Meanwhile, on the north coast, one Portrush councillor said he'd found this weekend slightly quieter than last week - but still pretty busy.
UUP representative Norman Hillis told the Belfast Telegraph: "There were more cars around, driving through Portrush - plenty of the vroom-vroom boys, as I call them, with their souped up motors and blaring music more than usual - but I think fewer people on the streets. I did see groups of youths swigging from bottles full of a clear liquid - which I, of course, presume was water."
The councillor said the police had to be summoned to clear away people playing football on the town's East Strand, where they were causing damage to the sand-hills - and he'd had a lot of complaints about overflowing rubbish bins and closed public toilets.
"It must be very frustrating for the restaurants and coffee shops, who can't open to serve all these potential customers," he added.
On Friday, Health Minister Robin Swann had urged everyone to remain vigilant over the weekend, and to act responsibly.
However, that night, a female police officer was kicked in the face and four young people were arrested after more than 200 youths gathered at Ballyholme beach in Bangor.
Officers also came under attack from sections of the crowd.
A 17-year-old man was charged with offences, including assault on police, and is expected to appear at Newtownards Youth Court on June 23.
An 18-year-old woman and a 16-year-old boy were released and were reported to the Public Prosecution Service while a 15-year-old boy remained in custody on Saturday evening.
North Down Ulster Unionist MLA Alan Chambers, the UUP's representative on the Policing Board, condemned the behaviour and said social distancing needed to continue to be taken seriously.
"I can understand that many teenagers and young people are feeling frustrated about the current lockdown, but that does not excuse some of the behaviour that took place at Ballyholme beach," he said.
"Everyone needs to heed the advice of the Health Minister Robin Swann and act responsibly at all times."