Shatt al-Arab

Shatt al-Arab is a 200-kilometer-long river that originates at the junction of the Euphrates and Tigris rivers in the Basra Governorate of southern Iraq's town of al-Qurnah. The river's southern end forms the Iran – Iraq border all the way to its mouth, where it empties into the Persian Gulf. The breadth of the Shatt al-Arab varies from 232 meters in Basra to 800 meters at its mouth. The waterway is assumed to have formed very recently in geological time, as the Tigris and Euphrates used to drain into the Persian Gulf via a passage further to the west. The Karun, a tributary that joins the waterway from the Iranian side, dumps a lot of sediment into the river, requiring constant dredging to keep it navigable.

The area used to be home to the world's largest date palm forest. The region had 17–18 million date palms in the mid-1970s, accounting for around one-fifth of the world's 90 million palm trees. By 2002, however, more than 14 million palms had been killed out by a combination of conflict, salt, and pests; this number includes around 9 million palms in Iraq and 5 million in Iran. Many of the 3 – 4 million trees that remain are in terrible condition.

Length: 124 miles (shared with Iran)