MEXICO CITY — The beachside dance floor was packed. The pulse of electronic music throbbed. In the middle of the pandemic, in the crowd of maskless dancers, some tourists commented to each other: "Tulum is back."

“There are parties almost every night,” said Maria Prusakova, 30, the founder of a public relations firm, who traveled to Tulum in July from San Francisco.

When the restaurants closed at 11 p.m., she said, the parties started at private villas. No one wore masks. Prusakova got sick at the same time as 12 of her friends. They all tested positive — in her case, only after she returned to San Francisco.

Prusakova is returning to Tulum for New Year’s Eve, when the city is typically packed with parties.