KOLKATA: Prime Minister Narendra Modi on Wednesday unveiled multiple metro projects across the country, including India's first underwater metro line in Kolkata.

The Rs 4,965-crore Howrah Maidan-Esplanade section of Kolkata Metro's East-West Corridor, which has the first transportation tunnel "under any mighty river in India", was inaugurated by the PM. The stretch also has the deepest metro station in the country -- the Howrah metro station.

After the inauguration programme, Modi took a metro ride from Esplanade to Howrah Maidan along with school children.

The under-river section of the tunnel is 520 metres long, and a train will take around 45 seconds to cross it, officials said.

From the function at the Esplanade metro station, the PM also inaugurated the Kavi Subhash-Hemanta Mukhopadhyay section of the New Garia-Aiport line and the Taratala-Majerhat section of the Joka-Esplanade line of the Kolkata Metro, the country's oldest metro network.

The Majerhat metro station is a unique elevated installation across railway lines, platforms and a canal, an official statement said.

Modi also inaugurated the Duhai-Modinagar (North) section of the Delhi-Meerut RRTS Corridor, Pune Metro's Ruby Hall Clinic-Ramwadi stretch, Kochi Metro's SN Junction to Tripunithura section and Agra Metro's Taj East Gate-Mankameshwar section.

The PM also laid the foundation stone for the extension of the Pune Metro between Pimpri Chinchwad and Nigdi.

These sections will help decongest road traffic and provide seamless, easy and comfortable connectivity, the statement said.

The section of the Agra Metro that was inaugurated will enhance connectivity to historical tourist places, it said.

The 17-km section of the RRTS will boost economic activity in the NCR, it added.