HAVANA — There's just no keeping Fidel Castro at home these days.

Thursday's visit to the aquarium in Havana's leafy Miramar neighborhood was a bit lighter, with Castro taking in a dolphin show and asking employees about the internal workings of the center, Cubadebate website said.

He regaled those in attendance with stories about how long he could hold his breath underwater as a youth — two minutes — and reminisced about an opportunity he had to swim with dolphins in Holguin.

Among those who met with the Cuban leader was Celia Guevara March, a veterinarian and the daughter of Ernesto "Che" Guevara, the Argentine revolutionary who fought alongside Castro during the Cuban revolution.

But Castro also turned serious, discussing his theory that a conflict pitting the United States and Israel against Iran would inevitably turn nuclear. He also warned about the threat of environmental disasters and global warming.

"The world lives between two tragedies," Castro told the employees. "War and the environment."

Visits to aquariums by former leaders don't usually prompt world headlines, but Castro has kept largely out of the public eye since undergoing emergency intestinal surgery in July 2006.