The small town of Mahabalipuram is situated about 55 km south of Chennai between Buckingham canal and Bay of Bengal. The name of city is spelt in various forms such as Mahabalipuram, Mahavellipur, Mavallipuram, Mamalaipuram, Mamallapuram, and Mallapuram (Crole, 1879). The shoreline at Mahabalipuram is characteristically oriented NE-SW. River Palar joins the sea on the southern side of Mahabalipuram. The geomorphic feature, the backwaters, the Buckingham canal-about 5 km west of the Mahabalipuram, with outlets at Covelong on the north and Kalpakkam in the south are significant. This area has contemplated stretches from Covelong on the north to Vayalur on the south with hinterland area of Vasavasamudram. In the near shore zone off Mahabalipuram, the seabed is uneven with rocky outcrops of granitic boulders with occasional sand patches, and it gradually slopes down towards east. There is a shoal called Tripalur reef, which is in the form of submerged rocks.