Iwo JimaI·wo Ji·ma
From Japanese 硫黄島 (iōjima). Prior to Japanese spelling reforms in the 1940s, this word was spelled いわうじま (iwaujima). Historical /au/ becomes IPA: [oː] via regular phonological rules resulting in [iwoːtoː]. With the exception of the low vowel /a/, /w/ is no longer phonetically realized. Thus, the word becomes IPA: [ioːjima]. The English spelling is based on the historical Japanese spelling, not pronunciation, as evident of retaining the "w". The long vowels are often ignored thus the loss of the macrons. Spacing is inconsistent as Iwojima is not uncommon. Iwo-Jima with a hyphen is also used.
The kanji 島 may be read as either jima (IPA: d͡ʑima) (the voiced form of shima due to compounding) or tō (IPA: toː). It is often the case that the correct reading of kanji is unclear, and sometimes multiple readings are recognized. Original inhabitants claim that the correct reading is "Iōtō". In June, 2007 Japan officially restored the name to Iōtō.