Nahal Sorek (Hebrew: נחל שורק, lit. Brook of Sorek), also Soreq, is one of the largest, most important drainage basins in the Judean Hills. It is mentioned in the Book of Judges 16:4 of the Bible as the border between the ancient Philistines and the Tribe of Dan of the ancient Israelites. It is known in Arabic as Wadi Surar.
The Midrash (Numbers Rabbah 9) states that the sorek is a "fruitless tree" (the word רק req means "empty" in Hebrew), implying a moral lesson and metaphor suggesting that Samson's involvement in his affair with Delilah was eventually "fruitless". However, another etymology suggests that "sorek" means "special vine" and refers to the grapes and wines grown in the area.
Nahal Sorek was the place where Delilah lived, and Samson came to meet her for the first time. It was also the place she enticed him to tell her the secret of his strength, and where he was eventually captured by the Philistines:
|“||And Samson went to Gaza... And it came to pass afterward, that he loved a woman in the brook/valley of Sorek, whose name was Delilah. And the lords of the Philistines came up to her, and said to her: 'Entice him, and see wherein his great strength lies, and by what means we may prevail against him, that we may bind him to afflict him...||”|
— Judges 16, 
|This section requires expansion. (April 2008)|
In the 19th century, Nahal Sorek served as an important connection between the two major cities in the area, Jaffa and Jerusalem. Because railways at the time were reliant on water sources, several surveyors who planned the first railway in the Middle East, the Jaffa–Jerusalem line, decided to use Nahal Sorek as the main route for the line. The digging of numerous tunnels for High-speed railway to Jerusalem is underway, which will avoid the Nahal Sorek route and shorten the line. However, the older railway along Nahal Sorek was also refurbished and should remain in use even after high-speed rail service begins (the Nahal Sorek line drops off/picks up passengers in a different area of Jerusalem than the high-speed rail will service, and as of 2013 is expected to continue to link Jerusalem to cities other than Tel Aviv and the David ben-Gurion airport).
While still being adjacent to the Tel Aviv–Jerusalem railway today, Nahal Sorek mainly serves as a tourist attraction. Several small water reservoirs exist along its route, notably near Tal Shahar and Yesodot. Waterfalls are located on several of its tributaries, including Ayanot Dekalim in Beit Shemesh, Ein Sifla on Nahal HaMe'ara, and others.