This tropical sea earns its name from the presence of coral reefs along most of its coasts. The Great Barrier Reef grows out to the edge of the Australian continental shelf, on the western side of the sea. Warm water enters from the Pacific, circulating weakly before leaving through the Torres Strait to the west, or to the south as the East Australia Current. The eastern and northern sides of the Coral Sea are marked by deep trenches, where the oceanic part of the Australian Plate is subducting. Volcanism has resulted in the Solomon Islands and the Vanuatu chain. Explosive eruptions in these islands can create pumice, a volcanic rock that floats due to gas bubbles trapped inside. Lumps of pumice are sometimes washed up on the western shore of the Coral Sea.