509 years ago a Portuguese explorer Ferdinand Magellan sailed across the Pacific Ocean and he named it Pacific which meant peaceful sea  every year the Pacific Ocean is sinking the main reason behind it is the movement of underwater tectonic plates but the good thing is that the more it is shrinking, with the same speed the Atlantic Ocean is increasing. Most earthquakes and tsunamis occur due to the tectonic plates present at the bottom of the Pacific Ocean most active volcanoes are also present at the bottom of the Pacific Ocean noted than 75,000 volcanoes are present in the Pacific Ocean Pacific tops the chart with the number of number of islands there are more than 25,000 islands present in the Pacific Ocean.