The River Thames
The Thames - pronounced 'tems' - is the river that winds its way through the heart of London, dividing it into [North London]? and [South London]?. The city was created some two thousand years ago as a port; this original location remains the city's core, and is known still as the City of London. The eastern end of the section of the river that passes through London is the Docklands, which were, from the 17th to mid-20th centuries, the busiest part of the city, playing home to a huge trade of seaborne shipping. Note - it's always described, archaically, as 'the River Thames', or just 'the Thames' - never 'the Thames River'.
There are river buses that can take you up and down the river, as well as numerous [River Cruises]? and also [Floating Restaurants]?. There are of course also numerous bridges passing over it and [River Tunnels]? passing under it.