A subduction zone is a region in the Earth's crust where one tectonic plate is being forced beneath another, causing it to sink into the mantle. This process occurs at convergent boundaries, such as those found along coastlines or other areas where two plates are moving towards each other. As the subducting plate moves deeper into the mantle, it can cause a variety of geological phenomena, including volcanic eruptions and earthquakes. Subduction zones are also responsible for creating some of the world's most active mountain ranges, such as the Andes in South America or the Himalayas in Asia.