Frontier unveils $399 unlimited summer flight pass, 8 new routes to Puerto Rico

Frontier Airlines is back with another all-you-can-fly pass that comes as it unveils a major expansion in Puerto Rico.

The carrier's new unlimited flight plan, dubbed the "GoWild! All-You-Can-Fly Summer Pass," is available for purchase starting Tuesday for an introductory price of $399 per year.

This pass is valid for travel between May 2 and Sept. 30, and includes an unlimited number of domestic and international flights.

If you subscribe to the pass, you can book domestic flights the day before departure. You can book and confirm international travel starting as early as 10 days before your flight.

Every time you fly using a flight pass, you'll be on the hook for mandatory government-imposed taxes and fees, as well as a base fare of just 1 cent. These bookings also do not include seat assignments or bags, both of which will cost extra.

Flights taken with the pass do not earn miles or elite status credit, but will extend the expiration of any Frontier miles that are sitting in your account.

Once the introductory pricing is phased out, the summer-only flight pass will cost $999 a year. This new summer-only flight pass joins the airline's unlimited annual pass that was unveiled last year.

Also, if you plan to fly with Frontier, the airline has good news for you. The carrier is growing its network in Puerto Rico with the addition of eight new routes, as you can see in the table below.

Once these flights launch, Frontier will offer a total of 19 nonstop routes to the island, crowning the airline as the largest carrier serving Puerto Rico by the number of markets served.

Frontier explains that this major growth push is "designed to meet the increased demand among leisure travelers and visiting friends and relatives traveling to and from the popular Caribbean island."

Interestingly, Ponce, Puerto Rico, represents a brand-new route-map pin for the airline, and it'll go head-to-head in the Orlando-to-Ponce market against JetBlue and Spirit.

Many of the other routes are operated by other U.S. carriers, though Frontier is coming in with introductory fares starting as low as $49.

For more details about Frontier's network and its all-you-can-fly pass, be sure to check out:

• Frontier Airlines' unlimited all-you-can-fly pass now valid for kids, includes $200 flight credit
• Frontier drops customer service calling, but does its online chat work?
• Would you fly Frontier to Europe? CEO Barry Biffle is working on that
• Frontier Airlines World Mastercard review