'Dashboard diners' are being blamed for a spate of illegal dumping at the Sally Gap in Co Wicklow.
Environmental group PURE says day-trippers who picnic in their cars are polluting the beauty spot.
Last year 200 tonnes of illegally dumped rubbish was removed from the Wicklow-Dublin uplands by PURE.
PURE project manager Ian Davis says there are two groups to blame.
"The reality is you have the same people who are throwing their rubbish out the windows. They're 'dashboard diners'; they finish their sandwich, they come along to this beautiful viewing point, then decide to leave all their rubbish here. We've seen it.
And then you get these guys coming up in the middle of the night in vans. They've collected waste and then they come up here and they dump it all out."