<P> Coordinates: 51 ° 30 ′ 11" N 0 ° 03 ′ 07" W ﻿ / ﻿ 51.503 ° N 0.052 ° W ﻿ / 51.503; - 0.052 </P> <P> The Thames Tunnel is an underwater tunnel, built beneath the River Thames in London, connecting Rotherhithe and Wapping . It measures 35 feet (11 m) wide by 20 feet (6 m) high and is 1,300 feet (396 m) long, running at a depth of 75 feet (23 m) below the river surface measured at high tide . It was the first tunnel known to have been constructed successfully underneath a navigable river and was built between 1825 and 1843 using Marc Isambard Brunel's and Thomas Cochrane's newly invented tunnelling shield technology, by Brunel and his son Isambard Kingdom Brunel . </P> <P> The tunnel was originally designed for horse - drawn carriages, but was never used for that purpose . Since 2010 it forms part of the London Overground railway network under ownership of Transport for London . </P>

When was the tunnel under the thames built