The Witham Navigable is a river navigation system located in Lincolnshire, England. It stretches approximately 40 miles from the city of Lincoln to the North Sea, allowing boats to travel between these two points. The river is an important waterway for both leisure and commercial activities, providing access to various towns and villages along its route. Originally constructed in the 18th century, the Witham Navigable has undergone several improvements to enhance its navigability. It features a series of locks and weirs that help manage water levels and facilitate boat passage. The river is also part of the Lincolnshire Waterways network, promoting tourism and recreational boating in the region.