Mekong Lowlands and Central Plains is a region of Cambodia and includes the following provinces: Kampong Cham, Kampong Chhnang, Kampong Thom, Kandal, Kratie to the west of the Mekong, Prey Veng, Svay Rieng, Phnom Penh, and Takeo.
Silk Island (Kandal Province. The Khmer name is Koh Dach.)
Silk Island is just off the coast of Phnom Penh (to the east of Diamond Island). You can book through a touring agency or go to the port north of the river side (not the one immediately north of Titanic Restaurant/KFC, keep going for another five to ten minutes until a paved walking area opens up again and you can walk over the to sea wall). There you can negotiate with drivers who have anchored their boats and are waiting for customers. To go to Silk Island for four hours (1 hour each way, 2 hours on the island) and have one of the boatmen show you around should run around USD30. (He may begin with a price of USD45.)
Silk Island has many workshops where Cambodian women are hard at work on making traditional silk and cotton scarves and other fabrics. The raw silk is often brought from other provinces, but they refine, dye, and make the products here. You can buy them and other silk products for prices comparable to the markets in Phnom Penh. (USD4 for a silk kromah, for example). They will discount. A lot of English is spoken by the workers.
The boatman will also take you to a restaurant. Specify how much you want to spend to eat beforehand, or he may take you some place that is pricey. He may ask for you to buy him a drink while you eat. There is a local pagoda to visit. The option of visiting an island school will be suggested. You can swim in the water or pay USD3 to swim in a pool. The island is a nice taste of rural Cambodian life. It is very quiet and a nice escape from hectic Phnom Penh. Don't feel like you have to do what the guide suggests. Tell him what you want to do.