Among London's many problems as it grew at the beginning of the nineteenth century was travel between the two banks of the river Thames, which held important ports that could accept shipping coming up the river from the channel. Bridges would interfere with that important trade, so in the years of the 19th century engineers began to examine the only other option: instead of going over, going under the river.
The first class of nuclear submarines were a learning experience for the Soviet Navy. The November class boats experienced numerous difficulties and accidents, culminating in what has been described as a potential “Underwater Chernobyl."