The Yarlung Tsangpo Grand Canyon is the world's deepest river canyon, deeper than the Grand Canyon by a considerable margin, though far less visited. The river makes a dramatic horseshoe bend around Namcha Barwa (7,782 m), one of the most beautiful and notoriously difficult unclimbed peaks, before plunging southeast into Arunachal Pradesh as the Brahmaputra.
Access from Bayi is via a long road to the canyon viewpoint area near Motuo. The full inner gorge is accessible only on strenuous multi-day treks requiring permits and local guides. Most visitors see the upper canyon from overlooks near the village of Pai, where the scale begins to become apparent. Even these viewpoints, reached in a day from Bayi, are impressive — the river churns far below through dense forest, with snow peaks rising beyond.