The owner of a riverboat tour company who took millions in payments for excursions that never happened was sentenced to nearly four years in prison Wednesday.

Bret A. Gordon, the former owner of Tom Harper Cruises in Newton, was sentenced in US District Court in Boston to 46 months in prison, followed by three years of supervised release, according to the US attorney’s office.

Gordon was also ordered to pay $2.9 million in restitution to victims, although it was unclear where the money would come from. The cruise company has filed for bankruptcy protection.

Gordon pleaded guilty on Nov. 4.

Stewart F. Grossman, the court-appointed trustee representing creditors in the bankruptcy case, has said that Gordon lost millions by gambling.

Gordon’s lawyer, John S. Day, has previously said that the bankruptcy stemmed from the delayed delivery of two chartered boats. He could not be immediately reached for comment on Wednesday.

Couples paid Tom Harper Cruises as much as $18,000 for a 2015 riverboat trip in Scotland on a vessel said to have been built for the queen of England, only to learn after arriving in Edinburgh that the trip was canceled.

In 1996, court records show, Gordon blamed a gambling addiction when pleading guilty to three counts of interstate transportation of stolen property after stealing $130,000 from an employer.

Israel Shaked, the founder and principal of Michel-Shaked Group, a Boston consulting firm, and a Boston University finance professor for 37 years, said he was so impressed with Gordon’s computer skills when he was taking a finance class in the 1990s that he gave Gordon a job registering participants for a $5,000 training program sponsored by the firm.

Shaked began receiving complaints from people who said they had paid for a course but were not registered. Gordon eventually admitted in court to stealing 127 checks totaling $130,000.

Tom Harper Cruises booked trips in places like Russia, Scotland, France, Spain, and Vietnam, routing customers to independent tour operators after adding a 25 to 35 percent markup, prosecutors said in court filings.

Megan Woolhouse can be reached at megan.woolhouse@globe.com.