Abu Musa(Arabic: أبو موسى)(Persian: بوموسا listen^ⓘ, IPA: [æbu mu'sɒ]) is an 12.8-square-kilometre (4.9 sq mi) island in the eastern Persian Gulf, near the entrance to the Strait of Hormuz. which are disputed between the United Arab Emirates and Iran over sovereignty, and are currently administered by Iran. Due to the depth of sea, oil tankers and big ships have to pass between Abu Musa and Greater and Lesser Tunbs, making these islands some of the most strategic points in the Persian Gulf. The island is under the administration of Iran, as part of the Hormozgan province.

Iranian inhabitants of Abu Musa call it "Gap-sabzu" (Persian: گپ‌سبزو), which in Persian means "the great green place". On old Persian maps, the island is called:

In recent centuries it, has also been called Bum Musa, Persian for "the land of Musa/Moses", instead of "Boum-Sou".

In Arabic sources, "Abu Musa" (Arabic: أبو موسى) comes from Abu Musa al-Ash'ari, a companion of Muhammad, who stayed on the island in 643 CE before battling the Persians.

Abu Musa island is located 70 kilometres (43 mi) south of Bandar-e Shenas and 59 kilometres (37 mi) north-northwest of Sharjah. Out of the 14 islands of Hormozgan, it is the farthest from the Iranian coast. Its highest point is the 110-metre (360 ft) Mount Halva and has Abu Musa city as the center of the island. The weather in Abu Musa is warm and humid, a better climate compared to other islands in the Persian Gulf. It has the most diverse ecosystem, but lacks suitable soil and water for farming. Fishing is the main industry for the locals.

It is served by the regional Abu Musa Airport.

The sovereignty of Iran on Abu Musa has been disputed by UAE, which inherited a dispute since 1971. By common consent, the island had been under the control of the Al-Qasimi ruler of Sharjah.

The island was actually covered by a protection treaty signed between the rulers of the Gulf and Britain as far back as in 1819.