Persian Gulf is situated at the south of Iran. It is almost 900 km long from the Strait of Hormoz to Arvand Rud, the border river between Iran and Iraq. The Persian Gulf is one of the warmest bodies of water in the entire Middle East. Oman Sea, situated at the south of Iran, connects the Persian Gulf to the Indian Ocean. With an approximate area of 903,000 km, the Oman Sea is surrounded by Iran and Pakistan at the north, Deccan peninsula at the east and Arabia peninsula at the west. Iran has got small ports at its shorelines with the Oman Sea like Chabahar, Gavater and Jask.
Since antiquity, the Strait of Hormuz and the Oman Sea have always been strategic waterways. Today, tens of gigantic oil tankers carry oil every day from the countries in the region through this route to different parts of the world. With an area of approximately 371,000 sq.km, Caspian Sea is the largest body of inland water all over the world, which is situated at the north of Iran. Its neighboring countries are Iran at the South, Turkmenistan at the SE, Kazakhstan at the NE and north, Russia at the NW and Azerbaijan at the SW.
The Iranian shorelines are approximately 992 km from the East to the West. The average level of of the Caspian Sea is 28m below sea level. There are geographic areas born at the Iranian shorelines because of the changes in the level of the sea, like Miankaleh Peninsula, Ashuradeh Island Hossein Qolly Bay, Gorgan Bay and Anzaly Bay. There is a vastly extended network of rivers in Iran most of which seasonally are filled with water. Some permanent rivers run from the Alborz or the Zagros to the Caspian Sea, Persian Gulf and Oman Sea. Some temporary rivers either run into a body of water or get dried before reaching any watershed.