Frontier Airlines, which has made a splash with 'all-you-can-fly' passes in the past is offering a summer-only pass this year, with an opening price of $399, as well as beefing up the map of its services to Puerto Rico.
The $399 price, covering flights between May 2 and September 30, is now on sale, but after an unspecified time the price will change to $999; it's possible the airline has set itself a limit on the number it will sell at $399.
Passholders will be able to book flights the day before flying, or 10 days before for international flights; there's no limit on the number of flights during the pass's validity.
It's not all free, of course. Leaving aside the token fare of one cent for each flight, passengers will still be on the hook for government and airport fees and any extras they pick such as baggage fees and seat selection charges.
The increased routes to Puerto Rico, six of them to San Juan and two to other island cities, make Frontier the airline with the most U.S. cities with direct service to Puerto Rico.