On a recent afternoon at the Venice Biennale, I walked into a bright blue portable john and peed for art.

Just outside the booth, a naked woman was submerged in a huge water tank, breathing through a scuba mouthpiece. My urine was about to pass along a tube from the toilet through several filtration systems, before topping up her glass chamber’s water level.

The performer, who would stay in the tank for at least four hours, was essentially living in other people’s waste. And she had plenty of donors. The toilet is part of a presentation called “Seaworld Venice” by the choreographer and theater-maker Florentina Holzinger that is undoubtedly the biggest talker of this year’s Biennale, which opens to the public on Saturday and runs through Nov. 22.

Although she has been a revelation for many in the art world, Holzinger has long been a star of Europe’s avant-garde theater and dance scenes. She is known for epic gross-out spectacles featuring naked performers, who sometimes undergo body modification procedures onstage.

In Venice, Holzinger’s exhibition unfolds inside the stark, modernist Austrian pavilion, which she has flooded with water. In one room, a naked woman spins around on a jet ski, making waves while onlookers gawk. In another, more stripped performers climb a huge revolving weather vane.

And then there are the toilets.

Constanza Pérez de Lara, 27, a regular Holzinger collaborator, gave me a warning as I headed for one of the two portable johns. “Please don’t do a number two,” she said: “It clogs the system.” Pérez de Lara then nodded toward a glass-fronted room full of vats and tubes that was filling with brown liquid. “See what happens,” she deadpanned.

Despite the event’s refined reputation, there is plenty of toilet humor at this year’s Biennale. Elsewhere, Aline Bouvy, representing Luxembourg, is presenting “La Merde,” a bizarre video about poop, which features an actor dressed as a giant piece of excrement.

Stilbé Schroeder, the Luxembourg pavilion’s curator, said the work was part of a scatological art history that stretched back to popular cartoons of the French Revolution era. More recent artists to work with or depict feces, Schroeder said, include the photographer Robert Mapplethorpe and the acclaimed British art duo Gilbert & George.

Poop is a subject that children talk about freely, Schroeder said, although in adulthood it is taboo. “Artists are people who like to use topics that are normally never discussed to stir up debate and emotion,” Schroeder said. You could see that as being provocative, she added — “but provocative means thought-provoking.”

Sometimes, however, transgressions can get in the way of deeper thinking.

Critics reviewing Holzinger’s stage works often focus on her spectacular stunts, like the roller-skating nuns in her opera “Sancta,” or the performer who hangs from hooks embedded in her skin in “Tanz,” an early work. Her more recent “A Year Without Summer” ends with a scene about elder care, in which performers wearing diapers appear to suffer from incontinence, spraying fake feces all over the stage.

That scene was foul, and a talking point — but when I saw it in Berlin last year, I found myself thinking more about the indignities of getting old.

Holzinger and her team insist there is something profound beneath the “Seaworld Venice” bombast. Nora-Swantje Almes, the show’s curator, said that filling the pavilion with water highlighted Venice’s peril as a city at risk from rising sea levels, while the toilet stunt might make some visitors think about their own water use and waste.

Realizing the project had been a lot of work, Almes added, Holzinger and her team worked with an Austrian environmental technology company to develop the water treatment system, and consulted experts to ensure that the show didn’t damage Austria’s historic pavilion, which dates to 1934, by filling it with water.

Holzinger said during a speech on Wednesday that she had initially wanted to create a totally submerged pavilion that visitors would have had to dive down to. But she dropped that idea, she said, after swimming in Venice’s canals and realizing that the water was too murky. (It also gave her “a bit of a rash,” she said.)

She was speaking onboard a boat that was cruising toward a special off-site performance in the Venetian lagoon that she was staging for a select group of curators, museum directors and reporters.

Early on Wednesday morning, three boatloads of V.I.P. guests — including Maurizio Cattelan, the artist who once installed a golden toilet at the Guggenheim Museum in New York — set sail in the rain for a floating platform about a mile from the shore. There, Holzinger’s team had set up bleachers in front of a barge with a crane on top.

In drizzle, and then a downpour, a group of musicians performed a pounding death metal track, with a singer roaring from the crane. Then the crane lifted and a golden bell rose from the lagoon, with Holzinger dangling like the clapper in the center. She swung her body from side to side, and the bell rang out, strong and deep.