A travel expert who has been to more than 90 countries says these are the best under-the-radar destinations

Darwin is at the top of Australia in the Northern Territory.

"It's closer to Asia than it is to Melbourne or Sydney," Brown said. Singapore is about 300 miles closer than Melbourne, according to Google Maps.

Despite the roughly four-hour flight between Darwin and these more popular Australian destinations, Brown says it's a hidden gem worth visiting because of its unique landscapes in the two bordering national parks, Mary River and Litchfield.

Brown travels to Darwin to see waterfalls, pools, and unique landscapes at Mary River and Litchfield National Parks.

"You're in this phenomenally different landscape from the Outback. Darwin feels as if you are not only hitting a new country but a new planet," she said. "It's unlike anything you've ever seen. And I think if you've traveled that far, you need to see that."

If you enjoy train travel, board the Ghan from Darwin to Adelaide. It is known as one of the most scenic railways in the world, with dramatic landscapes inaccessible by other transportation modes.

"If Europe is too expensive, go to Montreal," Brown said.

The city in Canada's eastern province of Quebec is just a 90-minute flight from NYC.

The French-Canadian city reminds Brown of Paris with historic architecture, cobblestone streets, and French culture.

Most Montreal locals speak French, and with a European aesthetic, it's easy to see why Brown considers it a comparable destination.

"Montreal is one of the best cities in the world," she said. "The 400-year-old city feels like Europe for half the cost."

She's particularly a fan of the public art scene. According to the city's website, more than 1,000 pieces are displayed around Montreal and are free to view.

Brown recommends taking yourself on a free tour. From the streets to the underground metro stations, Montreal is full of art.

"I love public art, and I love places that we are all allowed to inhabit with no money," Brown said.

A great place to start is Place Jacques Cartier, a public square filled with street artists and vendors, as BI previously reported.

In Central America, Costa Rica is a hot spot for tourists. From beaches and jungles to volcanoes and cloud forests, travelers can have a range of experiences in one trip.

But fewer tourists visit in the summer, as Costa Rica's wet season begins in late May and spans six months.

In the midst of the wet season, rain stops in Costa Rica in July, Brown told BI.

"It happens every year, just for the month of July," she added.

Since many travelers assume Costa Rica is rainy all summer, prices for flights and hotels decrease.

"You can go to the Caribbean side, where all the resorts are, or you can go to the interior, where there are volcanoes and rainforests," Brown said. "You're going to a place that everyone loves to go to. The biodiversity is off the charts. But you're going at a time when no one thinks to go."

For more ideas on where to travel this summer, Brown released the ultimate itinerary in a Summer Travel Trends Report in collaboration with Klarna.