The d'Entrecasteaux (French pronunciation: ​[dɑ̃tʁəkasto]) Ridge (DER) is a double oceanic ridge in the south-west Pacific Ocean, north of New Caledonia and west of Vanuatu Islands. It forms the northern extension of the New Caledonia–Loyalty Islands arc, and is now actively subducting under the Vanuatu/New Hebrides arc.The subduction of the DER is responsible for the anomalous morphology of the central part of New Hebrides arc whose movement more closely matches the north-east direction of the subducting Australian Plate (the rest of the New Hebrides arc rotate west in front of the southward expanding North Fiji Basin).