HAVANA — In the echoing cobbled walkway of an 18th-century fort that is home to part of the 11th Havana Biennial, an insistent clang emanates from an artwork in which a bronze bird continually hits a boat propeller with its beak. Behind that noise floats the melody of a Cuban son played by a trio. And then, above it all, comes another kind of sound: American voices, crying out in English, “Look at that!” and “I want you to see this!”


For much of the 2000s, President George W. Bush all but shut down travel between the United States and Cuba, and with it the stream of American art lovers who had helped nourish the Cuban art scene. But since President Obama began lifting many of the Bush-era restrictions on travel in 2009, the traffic has been flowing again over the bridge that links the American and Cuban art worlds.


Cuban officials say that more than 1,300 Americans — collectors, curators, dealers and others — have registered to attend this year’s biennial, close to the high reached in 2000, after the Clinton administration loosened years of travel restrictions. Under the recent changes, Cuban-Americans may visit whenever they want, and, as of last year, the United States government has expanded legal travel for other Americans, who may arrive on programs intended to foster contact with ordinary Cubans.


“We’re seeing a lot more foreign visitors this year, and among them a lot more Americans,” said Sandra Contreras, who runs the Villa Manuela gallery here. The change has been a boon, she added, explaining, “Even though we’ve developed markets in Europe and Latin America, American collectors are still our principal buyers.“


For Cuba, the biennial — which opened on May 11 and runs through June 11 — is a chance to experience international culture and show off the country’s own artistic evolution. The event has filled Havana’s exhibition halls, galleries, theaters and streets with sculpture, painting and street and performance art by 180 artists from 45 countries, according to the Wifredo Lam Center for Contemporary Art, which organizes the event. Dozens of Cuban artists are showing work in the official and unofficial spaces.


“You learn a lot from seeing this,” said María Teresa Cañarte, a pediatrician from the eastern province of Pinar del Río who on Tuesday was looking into two square “wells” made by the Chilean artist Iván Navarro, who used neon lights and mirrors to create an illusion of depth. “A lot of people here don’t get to travel and see art elsewhere. It opens our horizons.”


There is a smattering of American artists, including Andres Serrano, who has a show at a photography gallery in Old Havana, and Craig Shillitto, whose Paladar Project took 10 chefs to Havana to cook with 10 Cubans in a pop-up restaurant built out of shipping containers.


On May 11 the Russian-American artist Emilia Kabakov, surrounded by a throng of Cuban families, hoisted the sail of “The Ship of Tolerance” on a grassy space next to Havana Bay. Ms. Kabakov and her husband, Ilya, have built wooden ships in half a dozen locations, including Venice and the Egyptian desert, creating the sails from prints of paintings by local children. (She said the boat, which will be kept on land, will remain in Havana and could last a decade or more.)


On the Malecón, the curving sea wall that sweeps along Havana’s northern flank, a set of works by Cuban artists explores the subject of migration and flight, an emotional theme in a country where you have to ask permission to leave and where many have died trying to do so in makeshift rafts and boats.


In “Fly Away,” by Arlés del Río, the silhouette of an airplane cut into a chain-link fence suggests that an airliner has burst through. Esterio Segura’s “Homemade Submarines,” which transforms a vintage Chrysler, echoes the inventive and precarious vessels Cubans made during a mass seaborne exodus in 1994.


Passers-by paused to look at themselves against the backdrop of the empty sea in Rachel Valdés Camejo’s mirror installation, “Happily Ever After No. 1,” and to puzzle before “Nobody Listens,” by Alexandre Arrechea, a sculptural aluminum tree of ears that get smaller and smaller as they approach the top.


Across the bay, the sea-crossing theme continues at a wide-ranging Cuban show at the 18th-century fortress of San Carlos de la Cabaña. Hanging in a room are life-size sharks in human clothing, and the detritus of a shipwreck. It is the work of Alexis Leyva Machado, known as Kcho (pronounced catch-oh), whose small bronze bird pounds its beak against a propeller hanging from a rope, ringing an endless knell, next door.


On the fringes of the biennial, groups of connoisseurs, many of them American, were shuttling among galleries and studios, meeting with artists and snapping up work. Artists occupy an unusual and privileged place in Cuba, where they can not only push the boundaries of political critique further than many, but can also keep much of the money from sales.