There are all types of watercrafts available for tourists to enjoy the pleasure of a tour on the bluish or greenish waters of the lakes and lagoons of Kerala. Among them are a large number of houseboats of exotic designs and divers facilities. The houseboats available in Kerala are unique and peculiar, because they are made by converting old-model cargo-boats or catamarans used widely in the southern Kerala backwaters and canal waterways for transportation of cargo like rice, coconuts, copra oil, coir, pepper, cashew nuts, cardamom, etc. The foundation or chassis of the houseboats of Kerala are such broad country-crafts of ancient inland navigation.
At present these exotic cruise vessels are available and concentrated in southern Kerala, because of the largest lake in Kerala usually called Vembanad Lake, entrance to which is the natural harbour Cochin. The water-bodies in the area south of Cochin stretch about 50kms north south. The width of this lake varies at different areas. The widest backwater area includes Kumarakom, with many resorts and luxury hotels. As this center with a bird sanctuary and tranquil waters has already become an international tourist destination more and more houseboats are built, with attractive designs and facilities.
The coastal backwaters of Kerala, usually called lakes or lagoons in tourist literature, were formed a few thousand years ago, by geological processes of soil erosion from the highlands of the Western mountain range and the cultivated midlands. Alluvial deposits of centuries or millennia, coupled with the sand deposits by the waves of the Arabian Sea, gradually resulted in the formation of the present day backwaters in south-central Kerala coastal plains south of Cochin (Kochi) and north of Quilon (Kollam).
Lagoons are defined by geologists and geographers as “areas of relatively shallow water, situated in a coastal environment and having access to the sea, but separated from the open marine (sea) conditions (like waves) by a barrier (like sand-dunes built by waves of the sea) or a coral reef.
The Vembanad Lake, on its western side is thus separated from the Arabian Sea by a stretch of land formed from the ancient sand dunes. This separating stretch of narrow sandy terrain prevents ordinary sea waves from entering the inland water body and is helpless only before tsunami waves like the one that came four years ago.
Thus the narrow, but sufficiently wide, sandy barrier along the sea shoreline, ensures a tranquil and peaceful ambience in the Vembanad Lake.
A lake is defined as a mass of still water, situated in a depression of the landscape, without direct communication with the sea. Besides this definition, the term ‘Lake’ is also applied to widened part of rivers and to bodies of water, which lie along seacoasts, and in direct communication with the sea. In the case of the Kerala backwaters, like the Vembanad Lake, there are outlets into the Arabian Sea, through the Cochin harbour and other outlets south of Alappuzha at Thottappally Spillway.
Smaller lakes in the terrain are termed pond, tarn, loch and mere, according to size and position. There are many such lakes also in Kerala. Lakes created by man for electricity generation are also a geographical feature of the Kerala landscape. The reservoir lake at Thekkady offers boat rides through tiger wildlife sanctuary. Lakes, owing to their isolation from the great oceans, have peculiar physical, chemical and biological features.
The Kerala coastal plains are lowlands (some areas are below – sea – level like Netherlands) in close proximity to the Arabian Sea and have a number of Lakes. River water flows into these coastal lakes during the Monsoon rainy season and for a few months afterwards, making them fresh water lakes. But during dry season (From February to May) rivers go dry and freshwater flows from the highlands and midlands, stop and water from the sea flow into the interior making the waters of the coastal lakes brackish (salty). The Vemband Lake is a water body where a 5 km long barrier (bund) has been constructed during the 1950s to block entry of salt water from the Arabian Sea through Cochin harbour, situated at the mouth of the Lake.
The Primary source of lake water is atmospheric precipitation, which may reach the lakes by rain, rivers, spring and immediate run off from land surfaces.