The Scilly naval disaster of 1707 was the loss of four warships of a Royal Navy fleet off the Isles of Scilly in severe weather on 22 October 1707. Between 1,400 and 2,000 sailors lost their lives aboard the wrecked vessels, making the incident one of the worst maritime disasters in British naval history. The disaster has been attributed to a combination of factors, including the navigators' inability to accurately calculate their positions, errors in the available charts and pilot books, and inadequate compasses.