In Alleppey you will find many travel agencies that organize boat tours. Do some comparison shopping before reserving. If you do not trust any of the agencies, ask your hotel's staff.
To do the one day tour there are two types of boats: the rowing or the engine boats. The engine boat is faster, but noisier. The rowing boat is quieter, but slower.
If you want my opinion, take the rowing boat. You will appreciate the tranquility much more than the speed in the backwaters.
♥ Visit Tagulandang Island ♥