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 - 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 Riverside area (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 around 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 30 dollars. (They may begin with a price of $45.) The more people you take, the cheaper it is per person.
Silk Island has multiple places 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 on site. You can buy them and other silk products on site for prices comparable to the markets in Phnom Penh. ($4 for a silk kromah, for example) They are willing to discount. A lot of English is spoken by the workers.
The boat man will also take you to a restaurant - you should specify how much you want to spend to eat with him beforehand, or he may take you someplace 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 is offered to go visit a school on the island. You can swim in the water or pay $3 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 follow a guide - tell them what you want to do.