The Boscastle flood of 2004 (Cornish: An Lanwes Kastel Boterel 2004) occurred on Monday, 16 August 2004 in the two villages of Boscastle and Crackington Haven in Cornwall, England, United Kingdom. The villages suffered extensive damage after flash floods caused by an exceptional amount of rain that fell over eight hours that afternoon. The flood in Boscastle was filmed and extensively reported but the floods in Crackington Haven and Rocky Valley were not mentioned beyond the local news. The floods were the worst in local memory. A study commissioned by the Environment Agency from hydraulics consulting firm HR Wallingford concluded that it was among the most extreme ever experienced in Britain. The peak flow was about 140 m³/s, between 5:00pm and 6:00pm BST. The annual chance of this (or a greater) flood in any one year is about 1 in 400. The probability each year of the heaviest three-hour rainfall is about 1 in 1300 (although rainfall probability is not the same as flood probability).