Line 3 of the Xiamen Metro is a metro line in Xiamen. The line running from to , is long with 21 stations in operation. The line features a undersea tunnel. Construction began in August 2016 and the section from Xiamen Railway Station to Caicuo (Phase 1 & Phase 2 West section) was opened on June 25, 2021. The remaining section of Phase 2, from Caicuo to Xiang'an Airport is currently under construction. A Southern extension to Shapowei is also under construction.