Frequent flyers are well-versed in which airports have the best and worst Wi-Fi, but for those exploring new horizons this summer, it pays to know where wireless Internet is readily available, and where it’s a lost cause.

According to the Speedtest by Ookla results for the first four months of 2018, Seattle–Tacoma International Airport has the fastest airport Wi-Fi in North America. Seattle also beats out Gold Coast Airport in Australia, Congonhas-São Paulo Airport in Brazil, Dubai International Airport, Seoul Incheon International Airport in South Korea, Sheremetyevo International Airport in Russia and Mohammed V International Airport in Morocco.

Via JC Decaux

In second place in North America, we find Denver International Airport, which had claimed the top spot last year, followed by Calgary, which has the fastest Wi-Fi in Canada. Hartsfield–Jackson Atlanta International Airport, San Francisco International Airport, Philadelphia International Airport, Vancouver International Airport, Logan International Airport, Orlando International Airport and LaGuardia Airport also rated favorably.

The five worst-rated Wi-Fi systems included Phoenix Sky Harbor International Airport, Detroit Metropolitan Airport, Minneapolis–Saint Paul International Airport, Toronto Pearson International Airport and Montréal–Pierre Elliott Trudeau International Airport.

Wifi

“Nothing improves a traveler’s trip quite like reliably fast Wi-Fi can,” Ookla co-founder Doug Suttles said. “What our comprehensive analysis shows is that surprisingly only a few airports across the U.S. and Canada have recognized just what an impact this can have. Wi-Fi speed can make all the difference for the business traveler finalizing a presentation or a family downloading videos to keep their kids occupied.”

RELATED: 21 Airports You'll Actually Be Happy About Having A Layover In

Ookla maintains that many airports still need much improvement when it comes to free Wi-Fi service. "There are far too many airports on this list with a mean download of less than 10 Mbps. Free Wi-Fi is good. Free Wi-Fi that's fast enough to keep travelers happily entertained is even better," the company said. “Overall improvement is great, but it’s also important to note that speed still matters. For example, the mean download speed at Montréal–Pierre Elliott Trudeau International is still at the bottom of our list despite a massive percentage improvement.”