Thames Festival Trust presents TOTALLY THAMES - an exciting, new month-long celebration of London’s river featuring arts, music and community festivals; colourful regattas; thrilling river races; foreshore archaeology, exploration, environmental and educational activities; as well as river-linked activities in London’s 17 riverside boroughs. The Mayor's Thames Festival (1996-2012) Running 1996 - 2013, The Mayor’s Thames Festival was London’s largest free festival - a two-day outdoor celebration of London and the river Thames and a fantastic mix of art, spectacle and entertainment bringing over 800,000 Londoners together to celebrate their city and showcase London’s creativity.