It’s actually at least seven main routes through a complex array of islands, peninsulas and straits. There are more commonly used routes and less commonly used routes. Different routes were discovered by different explorers.
"We Went Through One of the Most Infamous — and Narrow — Straits of the Northwest Passage" is from the August 17, 2017 Energy and Environment section of The Washington Post. It was written by Chris Mooney and narrated by Jenny Hoops.