Harbour Crossing Tunnel

The Tsuen Wan line of Hong Kong's Mass Transit Railway (MTR) system includes a 1.4-kilometre (1, 500 yd) dual-tracked, reinforced concrete, immersed tube railway tunnel across Victoria Harbour, connecting Hong Kong Island to Kowloon.

Google Maps ↗ Wikipedia ↗

Tunnel data from Wikidata (CC0). Summary from Wikipedia (CC BY-SA).

Other tunnels in China

Delaware Aqueduct United States · 137 km Päijänne Water Tunnel Finland · 120 km Orange–Fish River Tunnel South Africa · 82.8 km Ishikawa Tunnel Japan · 78.5 km Brenner Base Tunnel Austria · 64 km Mont d'Ambin base tunnel France · 57.5 km Gotthard Base Tunnel Switzerland · 57.09 km Hong Kong–Zhuhai–Macau Bridge China · 55 km