Sinait is a third class municipality in the province of Ilocos Sur, Philippines. According to the 2015 census, it has a population of 25,640 people. It is the northernmost municipality of the province and is 36 kilometres from the provincial capital, Vigan, 46 kilometres from Laoag, and 441 kilometres from Manila. Because of its main commodity, garlic, Sinait is also known as the Garlic Center of the North. ^ Census of Population. "Region I ".