Puducherry:

Total area: 290 Sq. Kms. Puducherry is bounded on Tamil Nadu on it South, North and West side and on the East by Bay of Bengal. Some pockets are Puducherry is totally surrounded by Tamil Nadu. The region is a flat country of average elevation of about 15 metres above sea – level, intersected by the deltaic channels of River Gingee and the Ponnaiyar and other streams forming the main drainage basins, interspersed with lagoons, lakes and tanks. The coastal border has a length of 22Km, with a breadth ranging from four to six hundred metres. Superficially, the coast is flat and sandy.

Karaikal:

Karaikal District occupies an area of 157 square kilometres (61 sq miles approx.). Karaikal town which is situated 16 km. north of Nagappattinam and 12 km. south of Tharangambadi is the regional headquarters. Karaikal region is made up of the Municipality of Karaikal, and Communies of Neravy, Tirumalairajanpattinam, Thirunallar, Nedungadu and Kottucherry. Forming part of fertile delta, the Karaikal region is completely covered by the distributaries of Cauvery River. Covered completely by a thick mantle of alluvium of variable thickness, the region is flat having gentle slope towards Bay of Bengal in the east. It is limited on the north by the Nandalar and on the south east by the Vettar.

Yanam: Total area: 20 Sq. Kms. Yanam is surrounded by East Godavari district of Andhra Pradesh. The region is bounded on the East and South by River Godavari which discharges itself into the Bay of Bengal after flowing about 14 Km. towards South – east. The town of Yanam is located at a spot where the River Coringa and the Godavari separate to divide the region in two parts, one on the east and the other on the west. The entire region is composed of a flat, monotonous terrain without any distinct topographical feature.

Mahe: Total area: 8.69 Sq. Kms. The total area of Mahe is surrounded by North Malabar of Kerala state. Mahe is a small area bounded on the South – west by Arabian Sea, on the North by the River Ponniyam (Moolakadavu) and on the other sides by a stretch of Calcareous hills of medium height which are linked to the ghats by a series of wooded hillocks. The River Mahe which flows towards the west divides the region into two parts.