Canadians are still flying to the U.S. thanks to a mysterious and unexplained loophole.

While our shared land border and land modes of border travel (car, train, ferry and pleasure boats) remain restricted between the two countries, apparently there's nothing stopping Canadians from flying to the U.S. at any time.

U.S. Customs and Border Protection told CBC News that the current travel restrictions only apply to land-based methods of border crossing.

U.S. Customs didn't provide a reason why it's allowed, either, instead pointing to the restrictions currently in place to reduce the risk of spreading the virus.

Provided that they haven't visited any one of the countries prohibited by the U.S. within 14 days, Canadians can fly into the States for non-essential travel without hassle.

It doesn't work the other way around, however, as Canada has prohibited U.S. travellers from entering the country through all modes of transport.

But American tourists have started to trickle in using their own loopholes, anyway.

It was recently reported that a Texas family was spotted in Banff grabbing a bite on their way to Alaska. Healthy, non-symptomatic foreign nationals are allowed to travel through Canada for "non-discretionary purposes" with minor restrictions.

It's recommended that travellers book their flights online as some travel agents might not be aware this is allowed. Canadians flying back from the U.S. will still need to self-isolate for 14 days.

The U.S.-Canada land border will remain closed until at least July while some restrictions, like for immediate family reunions, have been eased.