Ko Singto, or Lion Island, sits offshore from the Khao Takiab end of Hua Hin. It is a small rocky island rather than a developed beach resort, usually seen on short boat outings, fishing trips, or sea-kayak excursions when the weather is calm.
The island is worth knowing about if you want Hua Hin to feel less like a long hotel strip. Do not expect facilities or a major attraction; the appeal is the quick escape onto the water, the view back to the coast, and the sense of the Gulf of Thailand opening just beyond town.