San Antonio, officially the Municipality of San Antonio, is a 5th class municipality in the province of Northern Samar, Philippines. According to the 2020 census, it has a population of 8,882 people. Its territory is coterminous with Dalupiri Island, just off the western coast of Samar Island at the south end of the San Bernardino Strait. The island's white beaches are considered an "undisturbed paradise" and future "premier tourist destination" in the Eastern Visayas region.