Treen (Cornish: Tredhin) is a hamlet in the parish of Zennor, on the north coast of the Penwith peninsula in Cornwall, England, UK. It lies along the B3306 road which connects St Ives to the A30 road. At Gurnard's Head nearby on the coast is one of the many cliff castles on the Cornish coast which was formerly a Coastguard Lookout. To the east of Gurnard's Head is Treen Cove. The area is owned by the National Trust.