They found groups of young people swearing and shouting abuse, some urinating in public view, with litter and empty beer bottles completing the scene.
Across the border in Inishowen on Sunday evening the scene at Stragill beach near Buncrana wasn't quite so bad, but not really in keeping with a glorious evening. One carload was blasting out techno, whatever about the families nearby, while further up the beach two cars were spinning around at high revs as parents reached for babies and children.
One of the court cases in today's paper reports how police arrested a man while responding to complaints about scramblers on the beach at Magilligan.
How is it that in other countries families seem able to come to beaches and indeed to the centre of towns, even until late at night, and enjoy themselves without fear of the anti-social behaviour of young people?
One factor is certainly the availability of drink, and the drinking culture that's so much part of our society, among young and old. Perhaps the guidance of parents has something to do with it, and the actions – or lack of action - of authorities ranging from the police to the council.
Groups dealing with young people complain that they get a bad press, and that the great majority don't create problems. It's also unfair to expect young people to adopt wholesale the values of the elders, whose 'wild days' are long behind them.
What is reasonable is that action should be taken on under-age young people drinking, and against those who supply them. And that the younger generation should show respect for those who share public spaces with them – and who also want to enjoy this beautiful summer to the full.