This was the dangerous work of his father, Mariano Rivera Palacios. It was also what uncle Miguel Rivera did. He died in a hospital after injuries at sea.
Miguel Rivera was lashed by ropes that broke loose from a hydraulic mechanism used to reel in fishing nets. This all happened in front of young Mariano, whose mouth and ribs were injured.
The death left a mark on Mariano Rivera. Better, he thought, to concentrate on baseball than the perils of a fisherman's life.
"From that moment, I think he became fearful," his father said. "From then on he began to practice more and go to the stadium."
He signed with the New York Yankees two years after his uncle died. He returned to fishing at times, but only when he needed money.
Alfredo Munoz, a childhood friend, remembers that Rivera's dreams lay beyond the sea. He recalls Rivera saying: "I want to be somebody. I want to be great."
And he was true to his word. He became the greatest reliever in baseball history. He spent all of his 19 seasons with the Yankees, freezing batters at the plate for a generation. Now, at 43 years old and with the most saves in the game, the long ride ends with his retirement after this season.
Mariano Rivera was born on Nov. 29, 1969, the first son of Delia Jiron and Mariano Rivera Palacios. Around this Pacific fishing village he is still known by the nickname "Pili." The town of 17,000 relies on fishing with 90 percent of the population employed buying, selling or catching fish.
"Mariano was a baseball player when he was still in the womb," his father recalled. He also played basketball and soccer, but baseball won out.
His childhood friends remember how Rivera hated to lose. When his team was behind, he'd throw the ball in the ocean and call it a tie.
In Puerto Caimito -- 25 miles west of the capital, Panama City -- Rivera and his friends played their baseball on the beach with tennis balls, or balls made from fishing nets. Bats were made of branches from trees in the mangrove swamps. Gloves were empty milk cartons.
That would change before long. He failed in a tryout as an infielder, but he signed as a pitcher with the Yankees for $3,500. He was sent to the Dominican Republic to play, and quickly moved to Tampa, Fla. His debut in New York came in 1995.
"I rushed to sign as his dad," his father recalled.
Baseball in Puerto Caimito did not begin with Mariano Rivera. After all, in the 1960s, a pitcher named Manuel Jiron signed with the Pittsburgh Pirates, though he failed to make it to the majors. Rivera soared to unimagined heights.
Rivera's father and mother have traveled often to see their son pitch. His father, once a captain on a sardine boat, likes to muse about his son's journey.
"Sometimes when I'm in Yankee Stadium, I'm watching from the stands and I say to myself: 'Look where Mariano has come from -- from Puerto Caimito, a town full of mud and a stinking fish meal plants. But this is what feeds us."