The kettuvallams (Kerala houseboats) in the backwaters are one of the prominent tourist attractions in Kerala. More than 2000 kettuvallams ply the backwaters.The kettuvallams were traditionally used as grain barges, to transport the rice harvested in the fertile fields alongside the backwaters. Thatched roof covers over wooden hulls, 100 feet (30 m) in length, provided protection from the elements. At some point in time the boats were used as living quarters by the royalty. Converted to accommodate tourists, the houseboats have become floating cottages having a sleeping area, with western-style toilets, a dining area and a sit out on the deck. Most tourists spend the night on a houseboat. Food is cooked on board by the accompanying staff – mostly having a flavour of Kerala.