The question has become a sticking point in negotiations between the two countries. For Cuban President Raúl Castro, returning Guantanamo Bay to Cuba is a sine qua non for a full rapprochement.
"In order to move forward towards normalization, it will also be necessary to return the territory illegally occupied by Guantanamo Naval Base," Castro told reporters in a press conference with Obama on Monday, according to Time magazine.
For its part, the U.S. has made it clear that returning Guantanamo is not up for discussion, at least for now. But scientists have proposed a third option for the land: turn Guantanamo Bay into a protected area for environmental research.
Joe Roman, a fellow at the Gund Institute for Ecological Economics at the University of Vermont, had the idea while traveling in Cuba last summer.
"I was trying to think of a future that could be pretty inspirational," Roman told The Huffington Post about his proposal for the research facility.
With James Kraska, a law professor at the Naval War College, Roman published an article in the journal Science last week proposing to convert the 45-square-mile section of Cuba's coast into a protected area for research on climate change and biodiversity. Converting the land into a park would allow scientists to conduct important studies, protect some of Cuba's well-preserved ecosystems and improve diplomatic ties between the U.S. and Cuba.
"We could confront one of biggest issues of 21st century -- climate change and biodiversity loss," Roman said.
The U.S. has controlled Guantanamo Bay since 1903. The U.S. Navy technically leases the land from the Cuban government -- at around $4,000 a year. But since the 1960s, Cuba has refused to cash the rent checks, arguing that the U.S. occupation is illegitimate.
One way to return the land and improve diplomacy would be to convert the area into a research center that would host both American and Cuban researchers." Joe Roman, Conservation biologist
Obama has vowed to close the base's infamous detention center, which holds prisoners taken captive in the war on terror, but he won't return the land occupied by the naval base. That could make it politically difficult to transform the base into a research park, said Jonathan Hansen, a Harvard historian and author of Guantánamo: An American History.
"Cubans would go totally nuts if [the U.S. government] is taking their base away and sticking a research facility there," Hansen told HuffPost.
While the Cuban government would likely oppose a park run by the U.S., a research facility co-managed by the U.S. and Cuba might work, Hansen said.
"That kind of talk is real, since [Cubans] see themselves as leaders in science and medicine," Hansen said. "Those are the kinds of projects for which there’s a lot of goodwill in both Cuba and the U.S."
Even if a research park would initially have to be managed by the U.S., putting a civilian research facility on the island could improve U.S.-Cuba relations and begin the process of returning Guantanamo to Cuba, according to Roman.
"The eventual goal is to return the land to Cuba," Roman said. "One way to return the land and improve diplomacy would be to convert the area into a research center that would host both American and Cuban researchers."
Right now, Roman and Kraska's proposal remains a vision, a rough sketch of a grand idea. But conservation seems to be a major point of agreement between Cuba and the U.S. Since normalization officially began in December 2014, two of the four agreements signed by U.S. and Cuban officials have addressed environmental conservation.
In the end, however, the U.S. will have to return full control of Guantanamo to Cuba, Hansen said, adding, "We won’t have good relations with Cuba if we hold on to [Guantanamo]."
"It's immoral that we have it," he said. "It's an imperialist enclave of the U.S. that was bought and kept under coercion."