The T-shirt and flip-flop wearing crowd has stormed the red carpet twice, marched down the Lido's main avenues in anti-war protests and on Sunday night they occupied the exclusive terrace at the Excelsior Hotel where actors go to see and be seen.
"That was our masterpiece, our crowning achievement so far," said Luca Casarini, an anti-globalization activist and one of the organizers of the anti-festival called "Global Beach."
Paparazzi may be lining up for glimpses of Al Pacino and Nicole Kidman, but the guests of honor at "Global Beach" are outspoken U.S. director Tim Robbins and anti-globalization icon Naomi Klein -- both in town to present new documentaries.
"I couldn't come here just for the ... rarefied celebrity culture," said Klein, whose documentary "The Take" about radical labor initiatives in Argentina thrilled the crowd.
"It's always important to cross over, this is where our roots are," said the author of "No Logo."
Curious starlets like Scarlett Johansson even made the trip down the beach for the unspooling on Sunday night of Robbins' "Embedded-Live," the digital documentary of his theater production "Embedded" about the Iraq (news - web sites) war.
The activists are squatting on a stretch of sand with abandoned cabanas that was once a resort for police and their families.
They have set up a huge movie screen on the beach for alternative films, cleared a space for camping and spruced up the dilapidated kitchen, which now turns out 5-euro pizzas compared with 5-euro croissants available at the Excelsior.
More than 100 students and activists of all ages have pitched tents on the site, which is watched over by cardboard lions and skull-and-bones flags. Many more turn out for the screenings, debates and all-night parties.
"Culture belongs to everyone. They're doing business with films like 'The Terminal' and fancy screenings," said Luca Trivellato, a 23-year-old cinema fan who traveled from Milan.
"We're showing that we can seize the initiative in culture just like we can seize the beach."
And if they follow through on their threats, "Global Beach" will stroll down the red carpet a few more times.