Tourist Desk organises seven-hour backwater cruises. See their website for full information.
During the trip you will visit a village where you will see men at work in a factory, women making coir ropes and you will be shown different spice plants: pepper, coffee, nutmeg, cloves etc. Everything, also lunch, is included in the price of Rs 425 p.p. (€ 8.50).
Not included is a tip for the villagers who show the coir making etc. They tour organisers don't pay them for their performance, they are supposed to show the tourists their job and pose for the numerous photos taken of them without getting anything in return.
I thought that the villages shared in the profit and I only learned after our tour that the villagers weren't paid at all. Without them the whole trip is less interesting as it would mean that you only see the rivers. It would be a good thing if tourists gave a small amount of money to the villagers. After all they make the trip memorable.