The houseboats are huge, slow moving, exotic barge used for leisure trips. They were once known as kettuvalloms. The original kettuvalloms were used to carry tonnes of rice and spices - a standard kettuvallom can hold up to 30 tonnes - from Kuttanad to the Kochi port. But now the appearance of it has been changed a lot to transform it to a floating paradise.

The kettuvallam or boat with knots- was so called because the entire boat was held together with coir knots only - not even a single nail is used during the construction. The boat is made of planks of jack-wood joined together with coir. This is then coated with a caustic black resin made from boiled cashew kernels. With careful maintenance, a kettuvallom can last for generations.

A portion of the kettuvallom was covered with bamboo and coir to serve as a restroom and kitchen for the crew. Meals would be cooked on board and supplemented with fresh fish from the backwaters. Today, the tradition is still continued and the food from the local cuisine is served by the Kuttanad localites, on board.

Now these kettuvallams attract many from around the world. While converting kettuvallams into houseboats, care is taken to use only natural products. Bamboo mats, sticks and wood of the aracanut tree are used for roofing, coir mats and wooden planks for the flooring and wood of coconut trees and coir for beds. For lighting though, solar panels are used.

Today, the houseboats have all the creature comforts of a good hotel including furnished bedrooms, modern toilets, cozy living rooms, a kitchen and even a balcony for angling. Parts of the curved roof of wood or plaited palm open out to provide shade and allow uninterrupted views. While most boats are poled by local oarsmen, some are powered by a 40 HP engine. Boat-trains - formed by joining two or more houseboats together - are also used by large groups of sight-seers.