The River Witham flows through Lincolnshire in a broadly eastward direction, running from Lincoln to Boston before emptying into the North Sea via the Wash. The navigable section from Brayford Wharf in Lincoln to Boston covers approximately 36 miles and is characterised by flat, rural fenland terrain throughout. The river has been used as a navigation since Roman times and connects with the Fossdyke Canal at Lincoln.

The paddling character is touring-oriented — flat water with no significant whitewater, making it well suited to canoes, kayaks, and stand-up paddleboards. There are five locks along the route, though portages are described as manageable. The main structural hazard is the High Bridge (known locally as the Glory Hole) in Lincoln, a medieval arch approximately 4.6 metres wide and 2.6 metres high at normal water levels. This passage becomes unnavigable during flood conditions and requires careful attention at all times. A licence is required to paddle the river; Paddle UK membership covers over 4,500 km of waterways in England and Wales and can be obtained for between £29 and £60 per year.

Notable landmarks along the route include Lincoln Cathedral, visible from the water and offering an unusual perspective on the city. The Glory Hole itself — the only British bridge still bearing secular medieval buildings — is a historically significant feature. At Fiskerton, the Fen Nature Reserve provides wetland and reed habitats supporting bitterns, marsh harriers, and the rare water parsnip. Further east, the Boston Stump (St Botolph's Church tower, 81 metres tall) becomes a prominent landmark on the otherwise flat horizon, particularly striking at sunset. At Anton's Gowt, paddlers can access the Witham Navigable Drains, a network of backwater channels not managed by the Canal & River Trust.

The area around Dry Doddington and Long Bennington offers accessible put-in points near road bridges with parking available. The Water Rail Way, a walking and cycling path following the river corridor on a disused railway line, runs alongside much of the route between Lincoln and Boston, providing a useful reference for navigation and access planning.