Man completes 7 marathons in 7 days while on 7-day cruise

An ultra trail runner is opening up about completing seven marathons in seven days, a feat he accomplished while on a Mediterranean cruise this summer.

Paul Manson of Scotland told ABC News' Danny New he decided to take on the challenge in August and reached out to Princess Cruises ahead of his seven-day journey aboard the cruise line's Enchanted Princess ship.

"And they were like, 'Is that even possible?' And I was like, 'I don't know,'" Manson recalled.

Despite not knowing if he could accomplish his goal, Manson set off on his unusual quest, beginning by running 26.2 miles through the Italian capital of Rome, where he ran past the Colosseum and other ancient landmarks.

Manson also ran through Naples in temperatures of 100 degrees Fahrenheit, and on another day at sea, he said he completed 185 laps aboard the ship, equaling 26.2 miles, the length of a marathon.

The ultra runner, who also shares his running adventures as "The Random Runner" on social media, also ran marathons through the mountains of Montenegro and two marathons in Greece, even finishing one at the site of the first Olympics in Olympia.

For his final marathon in Sicily, Manson ran as Mount Etna was erupting and spewing lava.

Manson said he ended up getting covered in ash and jumped into the ocean for a celebratory swim to finish.

ABC News has reached out to Princess Cruises for comment.