The redoubt is surrounded by a ditch or dry moat which is 30 feet (9 metres) from the top of the parapet and 25 feet (7 metres) wide. On the far side of the moat, a glacis or earth ramp slopes away to ground level. Both the moat and the glacis have been removed on the seaward side during construction of a sea wall and promenade in 1890. The floor of the ditch is traversed by five caponiers or covered galleries with loopholes that allowed the defenders to fire at any attackers who had reached that point. These are unique in any of the circular redoubts and are thought to have been added in the mid-19th century. Access to the main gate of the redoubt is across a wooden drop bridge, which is a modern reconstruction of the original, built in 2003 with help from the Royal Engineers. A second entrance from the ditch was created in 1957 by inserting a large doorway through the scarp wall into one of the casemates.