Toby Donachie, 19, of Cornwall, England, said workers twice failed to realize he had the wrong plane ticket and he realized when the plane was in the air he had boarded the wrong flight, The Local.se reported Friday.
"When they said that we were flying over Denmark, I understood that we were going the wrong way," he told Sweden's Expressen newspaper.
Donachie, who was headed to Biarritz in France for a training camp, said the airline sent him back to London from Malmo for free and put him up in a hotel overnight before flying him to his intended destination.
"I thought it was fun, I was laughing -- it was an adventure," Donachie said. However, he said he did not want to stay in Malmo because the beaches are better in Biarritz.
Donachie said workers told him they had the wrong headcount for the flight he was on because a child was hiding under a seat.
Ryanair officials said security staff are investigating the incident.