Kolkata: India's first under-river Metro becomes reality

India's first under-river Metro, Kolkata Metro's Green Line, opens after over 100 years. The underwater railway in Kolkata was proposed by British engineer Sir Harley Dalrymple-Hay in 1921. The dream of building an underwater tunnel beneath the Hooghly has finally come true. Kolkata's first underwater tunnel was built in 1931 by CESC for power cables.