Jose Salvador Alvarenga, 37, arrived in Majuro, the capital city of the Marshall Islands, Monday.
The long-haired fisherman was rescued after washing ashore on the tiny atoll of Ebon in the Pacific Ocean Thursday.
He originally set sail from Mexico on Dec. 21, 2012, for a day of shark fishing with a teenage companion he knew only as Ezekiel. A storm blew the fishermen off course, and soon they were lost and adrift.
Ezekiel reportedly died a month into the voyage. Exactly how the boy died or what happened to his body remains unknown, but Alvarenga says he survived the voyage by eating turtles, birds and fish, and drinking rain and turtle blood.
"It's hard for me to imagine someone surviving 13 months at sea," said U.S. Ambassador Tom Armbruster in Majuro. "But it's also hard to imagine how someone might arrive on Ebon out of the blue. Certainly this guy has had an ordeal and has been at sea for some time."
The U.S. ambassador described Alvarenga as a soft-spoken man and said he had complained of joint pain during their 30-minute meeting. He had a limp but was able to walk.
"Quite an incredible sea story of a man that went out fishing for one day and expected to report to his port on the West Coast of Mexico, but he was blown off by a storm. He talked about north wind, waves and being blown off course and losing a companion at sea as well," said Armbruster.
Alvarenga is a native of El Salvador but has lived in Mexico for 15 years and fishes for a man known as Willie. He catches sharks for 25 pesos per pound, which is equivalent to $1.90 per pound.
"He thanked God, initially, that he had survived," the ambassador said. "He's very anxious to get back in touch with his employer, and also with the family of Ezekiel. That's his driving motivation at the moment."
After being rescued, Alvarenga was taken to a local hospital for monitoring. He appears to be in good health.
Skeptics are now questioning whether his story is legitimate, wondering what happened to the teenage companion that was with him. Law enforcement officials are working on piecing his story together and verifying his claims.
There have been other cases of people surviving for months adrift in the Pacific Ocean. In 2006, three Mexican shark fishermen said they were lost at sea for nine months before being rescued near the Marshall Islands.
ABC News and The Associated Press contributed to this report.