History of the Republic of Venice of the Sea" ceremony was established in this period. Orseolo died in 1008. Venice's control over the Adriatic was strengthened by an expedition by Pietro's son Ottone in 1017, by which time Venice had assumed a key role in balancing power between the Byzantine and Holy Roman Empires. During the long Investiture Controversy, an 11th-century dispute between Henry IV, Holy Roman Emperor and Pope Gregory VII over who would control appointments of church officials, Venice remained neutral, and this caused some attrition of support from the Popes. Doge Domenico Selvo intervened in the war between the Normans of Apulia and
Gulf of Aqaba over Greater Syria. The Marine Twilight Zone Research and Exploration program (MTRX) was set up in 2003 by the Interuniversity Institute for Marine Sciences of Eilat to conduct research on the deep coral reef systems of the northern Red Sea. The gulf is one of the most popular diving destinations in the world. About 250,000 dives are performed annually in Eilat's 11 km coastline, and diving represents 10% of the tourism income of this area. The Landscape of Wadi Rum to the east of the northern edge of the gulf is a popular destination. Other destinations are the ruins of