The Grand Sluice is a significant water management structure located in Boston, Lincolnshire, England. Built in the early 18th century, it was designed to control the flow of the River Witham and facilitate navigation for ships. The sluice played a crucial role in the region's trade and agriculture by managing water levels and preventing flooding. This engineering marvel features a series of gates and channels that regulate water flow. The Grand Sluice is also historically important, as it contributed to the development of the Boston Haven and the surrounding area, enhancing economic activities and transportation.