Guilderton is a small coastal town north of Perth, Western Australia at the mouth of the Moore River in the Shire of Gingin. It was originally known as Gabbadah, an Aboriginal term meaning "mouthful of water" until its gazetting as a town in 1951. The river mouth regularly opens and closes depending on the seasons, and alternates between a closed lagoon and a tidal estuary. The town is a popular holiday destination for Perth residents who commonly refer to it as Moore River.