Barnston Island is an unincorporated island located in the Greater Vancouver metropolitan area of British Columbia, Canada. Most of it is part of Metro Vancouver Electoral Area A; the remainder is Barnston Island Indian Reserve No. 3, which is outside Electoral Area A limits and under the governance of the Katzie First Nation, headquartered across the river at their main reserve in Pitt Meadows. Although the island is unincorporated and not officially part of any municipality, mailing addresses on the island use Surrey as the city name.