Krakatoa (/ˌkrɑːkəˈtoʊə, ˌkræk-/), also transcribed Krakatau (/-ˈtaʊ/; Indonesian: Krakatau), is a caldera in the Sunda Strait between the islands of Java and Sumatra in the Indonesian province of Lampung. The caldera is part of a volcanic island group (Krakatoa Archipelago) comprising four islands: two of which, Lang and Verlaten, are remnants of a previous volcanic edifice destroyed in eruptions long before the famous 1883 eruption; another, Rakata, is the remnant of a much larger island destroyed in the 1883 eruption.

In 1927, a fourth island, Anak Krakatau, or "Child of Krakatoa", emerged from the caldera formed in 1883. There has been new eruptive activity since the late 20th century, with a large collapse causing a deadly tsunami in December 2018.

 

Note:   The above text is excerpted from the Wikipedia article Krakatoa, which has been released under the GNU Free Documentation License.