As she paged through Viking River Cruises’ glossy brochure one recent afternoon, Diane Moskal noticed a new way to save money with e-check.

Are e-checks a safe way to pay for travel?

As she paged through Viking River Cruises’ glossy brochure one recent afternoon, Diane Moskal noticed a new way to save money: If she booked the Waterways of the Tsars itinerary sailing from Moscow to St. Petersburg with something called an e-check, the cruise line promised to knock $100 off the fare.