Most of the backwaters of Kerala are fresh water. They provide not only transportation, but irrigation and drinking water to support a very large population.
There’s a manually operated lock that allows vessels to move in and out but keep sea water out. We pulled up, but no one could find the keeper of the crank.
After some protests and the payment of an ‘appropriate fee’ the crank handle appeared, and the large doors slowly closed behind us, and the one in front opened to allow us to continue our journey out toward the sea.