Connaught Tunnel is under a mountain range.
Connaught Tunnel . The Connaught Tunnel is a railway tunnel under the Selkirk Mountains in southeastern British Columbia , Canada , near the city of Revelstoke . The 5.022 mi tunnel carries the Canadian Pacific Railway main line under Mount Macdonald and replaced the railway 's previous routing over Rogers Pass , which had been struck by several deadly avalanches since its completion in 1885 . The Selkirk Mountains are a mountain range spanning the northern portion of the Idaho Panhandle , eastern Washington , and southeastern British Columbia .