The Travancore State Canal in Kerala-Times of India photographer on January 1, 1940.photo was taken before the use of motor boats and house boats and the arrival of tourists after 1960-1970

These boats are called kettu vallam;kettu means- that which is built over- and vallam- means -boat ;in malayalam language .In 1940 these boats were used only for transport ;mainly of agriculture products
when india got freedom in 1947 ;political activities  also became free .But most political parties misused such freedom to produce militant unions ,which led to recurrent strikes and lockouts ;leading to collapse of both industrial and agricultural activites;as seen today in kerala
luckily tourists got attracted to kerala during this period ;and the above boats were all converted into house boats