The kettuvallam (Houseboat) or 'boat with knots' - is so called because the entire boat is made up of nodes that coir - without using a single nail for construction. The boat is made of planks of wood joined with coir. The assembly is then coated with black resin made from cashew nut shells boiled. Regular maintenance keeps a kettuvallom for generations.

Part of kettuvallom is covered with bamboo and coir to serve as toilets and kitchen crew. Meals are cooked on board and supplemented with fresh fish from the backwaters. Today, this tradition is still alive and the food of the local cuisine is served by the local Kuttanad on board.