The Palestine Exploration Fund (PEF) was established in the middle of the 19th century in Great Britain. Its official purpose was to research and map the Holy Land, but it also collected initial intelligence in the region which was under Ottoman rule. In 1913 an expedition was sent to the Dead Sea to monitor and study the fluctuations of its shoreline. Reaching a protruding rock next to Ein Feshkha springs (Today’s Einot Tzukim nature reserve), they marked a line 2 feet above lake’s surface. Beneath it, they engraved the initials PEF. This mark can be seen to this day on the side of road 90, 2 miles south of Qumran. The line and the PEF are also painted in red.
Today (2020), the shoreline of the Dead Sea is 130 feet beneath the PEF mark, and it keep dropping about 3 feet every year.
A visit to the site can be combined in a guided day tour of the Dead Sea.