Koh Kret is a small island just outside of Bangkok located in the Chao Phraya River. A taxi (about an hour from Silom) will take you to the boat where it is literally a 2 minute boat ride across the river.
Koh Kret is a community of Mon people and famous for its handcrafted pottery (it's more fun that it sounds!) It still seems to be a place that has retained a lot of traditional charm and consists of a lot of tiny winding lanes filled with food stalls, pottery and lovely friendly people (and not too many tourists). Definitely worth the trip. Oh and try and find the lady that deep fries ice cream...an amazingly tasty heart attack on a plate!