Sarn Gebir were the Rapids of the Great River Anduin. They appeared as the river's course passed between the Emyn Muil, above the Falls of Rauros. As they were unnavigable rocks and stony eyots, a portage-way was built on the western bank of the river, facilitating travel with light boats from Wilderland to Osgiliath, until the Orcs of Mordor began to multiply.
While the Fellowship of the Ring navigated the Anduin, Aragorn was preparing for the Rapids, but they reached them sooner than he reckoned, on midnight of 23 February. The stream pulled them towards the eastern bank, where they were ambushed by Orc archers from Mordor. The Fellowship paddled away from the rapids. During the next day they portaged a few miles to the foot of the rapids and resumed their paddling on the morning of 25 February.
