A hidden lagoon is being used by coronavirus lockdown rule-breakers, some travelling 100 miles for a walk.
Police say they had "dispersed large groups of people" - some from as far away as Somerset, Bristol and Cardiff - to a beauty spot in south Wales.
It comes after police in north Wales reported 10 people for breaching Covid-19 laws after they made a 500-mile round trip to Snowdon from London.
"This is not essential travel," Gwent Police said.
The beauty spot - known locally as Blue Lagoon or The Canyons, near Pontypool - on the Torfaen, Caerphilly and Blaenau Gwent border, is the former Tirpentwys opencast coal mine.
The site is in one of worst affected coronavirus death rate areas of the UK and the local Anuerin Bevan University Health Board has recorded 223 deaths.
Parked cars are being found on a daily basis on the road leading to the lagoon.
"[There were] 22 cars there Saturday afternoon," Simon Creed commented on Twitter.
The picturesque lagoon is surrounded by coniferous trees and because of its remote location, the site should only be accessible to a handful of visitors living nearby.
"Officers have been out stopping vehicles, currently near the Blue Lagoon by Pantygasseg," said a spokesman for Gwent Police.
The force said on social media that "people have travelled from Cardiff, Bristol and Somerset".
"This is not essential travel," they said in a statement. "Please take your daily exercise in the area where you live."
The Welsh Government has ruled people should not drive to take their daily exercise and to avoid unnecessary travel.
"No journeys of any significant distance should be taken," it said.
"For example, just in order to exercise in the countryside or at beauty spots."