The title of "widest canyon" depends on how you define "width". If you're looking for the widest canyon by rim-to-rim distance, then the answer is Yarlung Tsangpo Grand Canyon in Tibet, China. This massive canyon stretches for over 500 km (310 miles) with a width of up to 504 km (313 miles) at its widest point.

However, if you're considering the width of the canyon floor, then the Fish River Canyon in Namibia wins the title. This canyon boasts an impressive width of 27 km (17 miles) at its widest point.

Ultimately, the "widest canyon" depends on your chosen definition. Both Yarlung Tsangpo Grand Canyon and Fish River Canyon are stunning natural wonders deserving of recognition for their impressive scale.