Marchioness disaster

The Marchioness disaster occurred on the River Thames in London in the early hours of 20 August 1989. The pleasure boat Marchioness sank after being run down by the dredger Bowbelle, near Cannon Street Railway Bridge. There were 131 people on the Marchioness. Some were members of the crew, some were catering staff and others were guests at a private birthday party. Fifty-one of them drowned. The Marchioness was built in 1923 and in 1940 was one of the little ships of Dunkirk.

More information on the Wikipedia page.