Chennai's topography is remarkably flat, with an average elevation of just 6.7 meters (22 feet) above sea level. The terrain is primarily characterized by sandy coastal plains that transition into slightly firmer, clay-rich soils further inland.
Because the city lacks significant hills or mountains, the highest natural point is St. Thomas Mount, a small hillock in the southern part of the city, rising to about 80 meters (260 feet) above sea level. The lowest point is at sea level along the Bay of Bengal.
The flat topography creates natural challenges for drainage, rendering the city susceptible to flooding during heavy monsoon rains. Coastal sand dunes, marshlands like Pallikaranai, and estuarine ecosystems near the river mouths are the primary topographical variations in an otherwise level landscape.
