Concerns are mounting for a missing man that disappeared off the coast in the north of Perth.

Police will search for a fourth day for 49-year-old Matthew Phillips,.

He was last seen at his Sorrento home on Monday.

His car was found at the Grace Darling park near the beach at Lancelin on Tuesday.

His diving equipment was not in the vehicle, leading police to believe he had gone into the water.

Mr Phillips is described as being about 182cm tall, and bald with blue eyes.

Anyone with information is asked to contact police immediately on 131 444.

Image: WA Police