You need to reach Damnoen Saduak early in the morning (before 9am) to take part in the floating markets. We went by tour bus from Bangkok and endured the hour-and-a-half journey over bumpy roads, driven by an ex-stock-car driver having a bad day! The more pleasurable way of travelling would have been by water-taxi or water-bus.
They are called "floating" markets as many of the stallholders ply their wares from wooden canoes or sampans. In addition to this, many of the buying public are transported in a procession of sampans up and down the canals. The markets are very hectic, with hordes of tourists making the pilgrimage every day. This said, the markets still give you a good idea of what trading was like in Bangkok.