Sun-starved Brits flocking to green-list Portugal will need to wear a face mask on the beach or be stung by a £85 (€100) fine.
The warning came after many lockdown restrictions were lifted, including a ban on foreign holidays from May 17.
There were 22 flights from the UK scheduled to land in Portugal on Monday, with most heading to the southern Algarve region.
In an unfamiliar welcome for travellers Algarve tourism office workers were handing out packs of hand sanitiser and face masks to flyers.
One arrival, Kim, 27, who flew in from Manchester to Faro, said: "It feels amazing. Happy, everyone's happy.
Maria Joao, 55, whose small shop in Lisbon airport sells drinks and snacks, said: "We were massively affected by the pandemic.
"It was so sad to see the arrivals gate empty. But today it's better. It's a breath of fresh air."
Portugal, which imposed a strict four-month lockdown to tackle a devastating Covid surge in January, has reopened restaurants and shops.
But some limits on numbers are still in place and restaurants must shut at 10:30 p.m.
Masks must also be worn while walking on the beach with rule breakers facing a £85 (€100) fine, and nightclubs and indoor bars selling only alcohol remain closed.
Local media reports that the fines will also apply to people 'playing football on the sand.'
"We are still living in a pandemic," Marisa Semedo, manager of a riverside cafe kiosk in Lisbon said. "They must take it easy, don't drink too much, don't get out of control because the British really like to drink."
Portugal is one of just 12 countries that have been named on the government's green list under its new traffic light system.
Travellers must still take a Covid test before flying out and book one for the return journey at their own expense.
There is however no requirement to quarantine unlike countries on the amber and red list.
