Bangkok has some floating markets that you can visit on your trip.
The best known is Damnoen Saduak, a place full of life and color, where you can find hundreds of boats selling food and fruit.However, today, it is above all a tourist attraction having lost some of its more genuine side.
If you are looking for an experience that comes closer to true Thailand, you should visit the Talin Chan, less touristy yet, still having a bit of everything.
Located 12km from downtown Bangkok, it is open all day and has a large local market nearby. There, you can take a long tail boat ride and get to know what is around. You will find a world of old wooden houses.
You can also opt for Amphawa, Bangkoks second most popular floating market. Located 90km away, it is fun and a real reflection of Thailand. Find souvenirs, lots of food and do not miss the small temple on the other side of river. Try to go early to avoid large crowds.