The Ring of Fire, which runs 40,000kms around the edges of the Pacific Plate, dips in and out of the ocean as it sweeps north from New Zealand in a wide arc including Indonesia, Japan, Russia, and the North and South American coastlines. Four of the largest eruptions of the past 10,000 years have occurred along its edges. Many of its estimated 1,000 volcanos are underwater, and of the 76 undersea volcanos stretching from New Zealand up through the Kermadec Arc towards Tonga, 80% are active.