In June 1722, Ashton was captured by pirates while fishing near the coast of Nova Scotia. In the Boston News Letter of 9 July 1722, Ashton was listed as being one of those captured by the pirate Edward Low.  As Ashton refused to co-operate with the pirates, he was often threatened. He managed to escape in March 1723 when the pirates landed at Roatán Island in the Bay Islands of Honduras, hiding in the jungle until the pirates decided to depart without him. He survived for 16 months, in spite of many insects, tropical heat and alligators. In the beginning he seems to have eaten only fruits, because he only had his hands to collect food; he could not kill any animal. He had no equipment at all until he met another castaway, an Englishman. The Englishman disappeared after a few days but he left behind a knife, gunpowder, tobacco and more. Ashton could now kill tortoises and crayfish and make fires to have hot meals. Ashton was finally rescued by the Diamond, a ship from Salem, New England.

Philip Ashton (born in 1702) stayed as a castaway on uninhabited Roatan Island in the Bay of Honduras for 16 months in 1723-1724. His memoirs about his solitary stay were not believed by everyone; some people believed the book was a novel in the style of Robinson Crusoe. However, unlike Robinson Crusoe, Ashton was genuine; he was born in Marblehead in New England and married twice in his lifetime.