Иберия түбегінің ең ұзын өзені – Тахо

Longest river on the Iberian Peninsula
a river in the Iberian Peninsula

The Tagus ('/t//eɪ//ɡ//ə//s/ TAYgəs; lang es ˈtaxo; Tejo ˈtɛʒu; see below) is the longest river in the Iberian Peninsula. The river rises in the Montes Universales near Teruel, in mid eastern Spain, flows , generally westward, and empties into the Atlantic Ocean in Lisbon.

The river's Latin name is Tagus. While the etymology is unclear, the most probable etymological origin for the hydronym Tagus is Indo European *(s)tag ('to drip').

The lower Tagus region in Portugal is a seismically active area. Major earthquakes in the Lower Tagus include those of 1309, 1531, and 1909.

Tagus river is one of the few rivers in the world to have an inverted delta. Its delta is wider at the beginning and narrows down as it approaches the sea, contrary to a typical delta. This is because it flows into the sea through a small opening in a valley. Although due to sedimentation, this delta is now only very partially inverted, with the valley now mostly filled with sediment. The delta is about 15 km wide and 25 km long, but its exit into the sea is only 2 km wide. It thus forms a large lagoon with large and very shallow sand banks which go uncovered during low tides. The delta used to be even bigger thousands of years ago.

The Pepper Wreck, properly the wreck of the Nossa Senhora dos Mártires, is a shipwreck located and excavated at the mouth of the Tagus between 1996 and 2001. The Tagus river basin comprises 42 v=sup and is the river basin with the most protected areas in Spain.