Guiuan is a municipality located in the province of Eastern Samar in the Philippines. It occupies the southeastern extremity of Samar Island and includes several adjacent islands, situated between the Leyte Gulf and the Philippine Sea.
The town is recognized as the surfing capital of the Visayas due to its coastal geography. According to the 2024 census, Guiuan has a population of 52,749 people, making it the most populous municipality in Eastern Samar and the second most populous administrative division in the province after Borongan.