Pacific Ocean width at about 5°N latitude, where it stretches approximately from Indonesia to the coast of Colombia—halfway around the world, and more than five times the diameter of the Moon. The lowest known point on Earth—the Mariana Trench—lies below sea level. Its average depth is , putting the total water volume at roughly . Due to the effects of plate tectonics, the Pacific Ocean is currently shrinking by roughly per year on three sides, roughly averaging a year. By contrast, the Atlantic Ocean is increasing in size. Along the Pacific Ocean's irregular western margins lie many seas, the largest of which
Southern Ocean four toothed whales. The largest of these, the blue whale ("Balaenoptera musculus"), grows to long weighing 84 tonnes. Many of these species are migratory, and travel to tropical waters during the Antarctic winter. Five species of krill, small free-swimming crustaceans, have been found in the Southern Ocean. The Antarctic krill ("Euphausia superba") is one of the most abundant animal species on earth, with a biomass of around 500 million tonnes. Each individual is long and weighs over . The swarms that form can stretch for kilometres, with up to 30,000 individuals per , turning the water red. Swarms usually remain