Paleoceanography![Figure][1] Integrated Ocean Drilling Program expedition in the Gibraltar gateway. PHOTO: JOHN BECK/IODP/TAMU The trickle of water that began to flow from the Mediterranean Sea into the Atlantic Ocean after the opening of the Strait of Gibraltar turned into a veritable flood by the end of the Pliocene 2 to 3 million years ago. It then began to influence large-scale ocean circulation in earnest. Hernandez-Molina et al. describe marine sediment cores collected by an ocean drilling expedition (see the Perspective by Filippelli). The results reveal a detailed history of the timing of Mediterranean outflow water activity and show how the addition of that warm saline water to the cooler less-salty waters of the Atlantic was related to climate changes, deep ocean circulation, and plate tectonics. Science , this issue p. [1244][2]; see also p. [1228][3] [1]: pending:yes [2]: /lookup/doi/10.1126/science.1251306 [3]: /lookup/doi/10.1126/science.1255553