Olbia or Arsinoe was an ancient city in the Regio Troglodytica upon the western coast of the Red Sea

Red Sea

The Red Sea is a seawater inlet of the Indian Ocean, lying between Africa and Asia. The connection to the ocean is in the south through the Bab el Mandeb strait and the Gulf of Aden. In the north, there is the Sinai Peninsula, the Gulf of Aqaba, and the Gulf of Suez...

 between Philoteras (Quseir or Kosseir) and Myos Hormos

Myos Hormos

Myos Hormos was a Red Sea port constructed by the Ptolemies around the 3rd century BC. Following excavations carried out recently by David Peacock and Lucy Blue of the University of Southampton, it is thought to have been located on the present-day site of Quseir al-Quadim , eight kilometres north...

. (Strabo

Strabo

Strabo, also written Strabon was a Greek historian, geographer and philosopher.-Life:Strabo was born to an affluent family from Amaseia in Pontus , a city which he said was situated the approximate equivalent of 75 km from the Black Sea...

 xvi. p. 769; Steph. B.

Stephanus of Byzantium

Stephen of Byzantium, also known as Stephanus Byzantinus , was the author of an important geographical dictionary entitled Ethnica...

 s. v. ). The city was renamed from Olbia to Arsinoe by Ptolemy II in honor of Arsinoe II of Egypt

Arsinoe II of Egypt

For other uses see, ArsinoeArsinoë II was a Ptolemaic Greek Princess of Ancient Egypt and through marriage was of Queen Thrace, Asia Minor and Macedonia as wife of King Lysimachus and later co-ruler of Egypt with her brother-husband Ptolemy II Philadelphus For other uses see, ArsinoeArsinoë II...

, who was both his sister and wife. According to Agatharchides

Agatharchides

Agatharchides of Cnidus was a Greek historian and geographer .-Life:He is believed to have been born at Cnidus, hence his appellation. As Stanley M...

 (de Rub. Mar. p. 53), there were hot springs in its neighborhood. The city stood nearly at the point where the limestone range of the Arabian hills joins the Mons Porphyrites, and at the southern entrance of the Gulf of Suez

Gulf of Suez

The northern end of the Red Sea is bifurcated by the Sinai Peninsula, creating the Gulf of Suez in the west and the Gulf of Aqaba to the east. The Gulf of Suez is formed within a relatively young, but now inactive rift basin, the Gulf of Suez Rift, dating back about 28 million years...

(the Heroopolite Gulf).