Krakatoa Volcanic Island, Indonesia

The Smithsonian Institution's Global Volcanism Program cites the Indonesian name, Krakatau, as the correct name but says that Krakatoa is often employed. This has been attributed to a sub-editor at The Times (who may have typographically swapped the 'a' and 'o' of the Portuguese spelling) interpreting telegraphic reporting on the massive eruption of 1883. Also, like Egypt a couple of decades earlier, Polynesia (South Pacific) was in vogue in the late 19th century, and the Polynesian-like suffix -oa (as in Samoa) may have caught on as a result. While Krakatoa is more common in the English-speaking world, the Indonesian Krakatau tends to be favored by others, including geologists. Rogier Verbeek seems to have started the modern convention of using Krakatau for the island proper and reserving Rakata for the main cone.
Geographical setting
Indonesia has over 130 active volcanoes, the most of any nation. They make up the axis of the Indonesian island arc system, which was produced by northeastward subduction of the Indo-Australian Plate. A majority of these volcanoes lie along Indonesia's two largest islands, Java and Sumatra. These two islands are separated by the Sunda Straits, which are located at a bend in the axis of the island arc. Krakatoa is directly above the subduction zone of the Eurasian Plate and the Indo-Australian Plate where the plate boundaries make a sharp change of direction, possibly resulting in an unusually weak crust in the region.