The group of six from the north-east broke lockdown rules to travel to Kisdon Force, where they pitched their tent above a path leading to the waterfalls on the River Swale.
Keld Lodge owner Matthew Teague spotted the group hiding in the trees while he was walking his dog, while they knocked on the door of his neighbour Jacqui Giles on Sunday morning asking to use her landline because they had no mobile phone signal or transport back home.
Mr Teague later posted photos on Facebook showing the mess the wild campers had left - including chairs, beer bottles and the tent itself.
They eventually left the area in a hired minibus, having endured extreme weather including heavy rain which Mr Teague believed would have flooded their poorly-sited tent.
Kisdon Force was also hotspot for 'lockdown parties' last summer, when young people turned up to pitch tents and drink near the falls during a heatwave in May.
Ms Giles added: "Knocking on our door at 8.15am (7.15am real terms), pleading to use the phone to call Sunderland as he needed to get out of Keld and had no transport or phone signal was a bit of a shocker. His five other friends were hiding around the corner. I would never had answered the door if I had known.
"If you are going to break the law, look at the weather forecast before letting your transport out of the area leave on a two-hour drive."
Local residents have now organised a working party to clear the litter.