Kirkby Shoal is a small shoal area with depths of less than 10 fathoms (18 m) extending about 150 yards (140 m) westwards and south-southwestwards, about 3.4 km (2.1 mi) from the summit of Shirley Island, Windmill Islands, and 0.15 mi (0.24 km) northwest of Stonehocker Point, Clark Peninsula.