Most volcanoes occur in the basin of the Pacific Ocean, also known as the Ring of Fire. Most volcanoes are situated on the edges of tectonic plates. One of the largest of these tectonic plates, the Pacific plate, is the area around which the majority of volcanoes lie.
According to National Geographic, the Ring of Fire, which lies around the Pacific tectonic plate, is home to the most volcanoes and the majority of seismic activity. There are 452 volcanoes dotting the Ring of Fire, which is about 75 percent of all the world's volcanoes. This 25,000-mile-long ring includes volcanoes on Antarctica, extends along the coast of South America, up Central America and Mexico, along the West Coast of the United States and the coast of California, marches across Alaska to Russia, extends down to Japan, over the Philippines, down to New Zealand and back to Antarctica. It also includes volcanoes in Hawaii and other islands in the Pacific Ocean.
Although it is less obvious, there is volcanic activity along the ocean floor in the Ring of Fire. According to Penn State, these underwater volcanoes are the most active in the world. Of the five most active surface volcanoes, three of them are on the Ring of Fire. The other two are in Italy.