Koh Racha is one of the most beautiful islands in the Andaman Sea and is handily located close to Phuket. The Islands consist of two islands, Koh Racha Yai and Koh Racha Noi.
Closest to Phuket is Racha Yai. Decked with snow white sand, this island has the consistency of talcum powder. On the east coast is a bay that is fine for diving even during rainy season.
You can also visit Racha Noi, located a little to the south of Koh Racha Yai. This uninhabited island has more rocks than beaches. There is a small bay on its west coast that is ideal for fishing. The main activities here are scuba diving and snorkeling.
(http://www.thephukettravel.com/th/phuket-island/koh-racha-yai-phuket/)