Seven Third Summits Sumantri () and Ngga Pulu (). The definition of "continent" is a matter of some dispute among mountaineers seeking to complete this challenge. The main ridge of the Greater Caucasus range is generally considered to form the boundary between Europe and Asia. In that case, Mount Elbrus () and Dykh-Tau (), are the two highest mountains in Europe. Excluding the Caucasus Mountains, Mont Blanc () and Monte Rosa () would be Europe's two highest mountains. The Australian continent is defined as comprising the mainland of Australia and proximate islands on the same continental shelf, including Tasmania and New Guinea. In
Mount Erebus Mount Erebus Mount Erebus () is the second-highest volcano in Antarctica (after Mount Sidley) and the southernmost active volcano on Earth. It is the sixth-highest ultra mountain on the continent. With a summit elevation of , it is located in the Ross Dependency on Ross Island, which is also home to three inactive volcanoes: Mount Terror, Mount Bird, and Mount Terra Nova. Several craters are located at the summit, including Side Crater, a nearly circular crater named for its location on the side of the main summit cone. The volcano has been active since about 1.3 million years ago and