The Thames (also known as the Styx) is a river, quite big one, out of which a number of smaller rivers flow. Hence the etymology of the name: 'Thames', pronounced 'Tems', a corruption of 'Stem'. The source of the Thames has long been a topic of debate, until it was discovered in Zimbabwe under a broken paving stone.
Visitors to the Thames should note that the native language of Thamesfolk is the Cockney Rhyming Slang. Most good travel agents can probably recommend a good phrase book.
For most of its course, the river flows due east, but there are places where it flows due north or due south. There is even one section where it flows northeast and another where it flows southeast, but this is the exception; due east, north, or south is by far its most common course. The river never flows in more complicated directions such as north-north-east, and its width is constant throughout the entire course, which makes mapping the river a fairly easy job.
It also flows through London. During the Middle Ages into Elizabethan times a winter fayre was held on the surface of the river between December 13th and 24th. This was really just a joke that the Londoners played on the numerous visitors to London, as the river never actually froze. Many people were therefore drowned and the festival rarely lasted beyond its first day.
Recent high-level discussions have taken place to reinaugurate the winter fayres as a way of ridding the city of the hordes of Australian travellers and American tourists. Prime Minister Tony Blair's apparent fondness for George W. Bush and comedy Australian 'Prime Minister' John W. Howard together with his feigned disdain for Mayor Ken Livingstone are really just play-acting. All this time he has been secretly plotting with Ken to lull Dubya and his fellow septics to their watery doom. There, I've said it.
The Thames embankments (a railway runs through them) were built by Ken Livingstone's predecssor Joseph Bazalgette (aka Basilisk), based in Spring Gardens (see Zebedee) which had a trick fountain, managed by a trick cyclist.