A woman has been rescued from the water off Auckland's coast today.

The woman, understood to be aged about 20, was reported to be in trouble about 300 metres off the shore of Maraetai about 12.50pm.

Coastguard operations manager Ray Burge said the woman was picked up by one of its crews about 1.15pm.

He said the woman was in the care of St John ambulance staff by 1.30pm.

She had reportedly "taken on some water" and was given first aid, including oxygen, by those first on the scene.