Travelers can visit iconic destinations like Banff and Jasper without paying entrance fees.A wooden walkway through Jasper National Park.Credit: Tanya Nikolic/Travel + LeisureWith stunning glacier-fed lakes, some of the largest dark sky preserves in the world, and breathtaking fjords, there are plenty of incredible national parks to explore across Canada. And this summer, America’s neighbor to the north is offering free admission to explore.From…