The Marine Liner (マリンライナー, Marin Rainā) is a rapid train service in Japan operated by West Japan Railway Company (JR West) and Shikoku Railway Company (JR Shikoku) since April 1988.

Some early morning and late evening trains make additional stops at intermittent stations on the Seto-Ohashi and Yosan lines.

As it is classified as a "Rapid" (快速, kaisoku) service, only a standard fare is charged for using the Marine Liner.

A crew change for the train driver and conductor occurs at Kojima, the boundary station between the two operating railways.

The Marine Liner service was introduced in April 1988, using 3-car 213 series EMUs formed as three-car, six-car, or nine-car formations.