Ko Sak (เกาะสาก) is an island off the coast of Pattaya.
Six hundred metres north of Ko Laan is Ko Sak, a small island shaped like an upturned horseshoe. There are two connecting beaches to the north and south. Along the south shore are ranges of corals. Accommodation is available.
The northern beach is popular for swimming and snorkeling, and the southern beach is a good place to see coral.