With a total length of 244 km*, the longest river in Kerala is the Periyar. Second and third are the Bharathapuzha (Nila) (209 km*) and Pampa (176 km*) respectively. Puraparamba and Kalnadu with a length of just below 10 km, are the shortest rivers. The Pampa which originates from Peermedu near Sabrimala is considered a holy river by the Hindus. These large and small rivers, along with their tributaries, distributaries and an innumerable number of streams and rivulets criss-cross the land making it green, attractive and fertile. Many of these rivers serves as inland waterways in many part of the state. Water from these rivers is used for irrigational purposes, drinking, hydro electric power production etc. They also serves as grounds for inland fishing.

Unlike the rivers of north India, which arise from the Himalayas and are both rain-fed and snow-fed, rivers of the south cannot be treated as a perennial source of water supply. This is because all these rivers are comparatively small and are entirely rain-fed with the result that many of them shrink into rivulets or dry up completely during hot seasons.
List of Major Rivers
Kerala Beaches and Islands

Lakes and Backwaters of Kerala

'Backwaters' or 'Lagoons' are shallow bodies of water separated from the open sea by land. Because of this separation from the sea, Backwaters are free from the pounding action of waves. Backwaters are one of the most alluring and economically valuable features of Kerala. These include lakes and ocean inlets which stretch irregularly along the coast.. The biggest backwater is the Vembanad lake with an area of 260 sq.km.

Second comes the Ashtamudi which covers an area of 55 sq.km. Sastamkota lake is the largest natural fresh water lake of the state. It extends over an area of 4sq.km. Other important backwaters are Veli, Kadhinamkulam, Anjuthengu (Anjengo), Edava, Nadayara, Paravoor, Kayamkulam, Kodungallur (Cranganore) and Chetuva. The deltas of the rivers interlink the backwaters providing excellent inland waterways along the lower and costal areas of the state. Backwaters serves as hot spots of Kerala tourism. The picturesque lagoons and backwaters of the state, attracts a considerable number of tourists each year. Backwater tourism include cruises on luxury house-boats, boating, boat races etc. Nehru Trophy boat race, one of Kerala's most famous boat races is held each year on the Punnamada backwaters of Alappuzha district.

* The length of the rivers are approximate measures and are likely to vary with time and season.