The geological collections at SIO are essentially a library of priceless geological samples that come from the seafloor and subseafloor of Earth’s oceans and lakes. The collections holds about 7500 deep ocean cores, more than 3500 deep sea dredges, and approximately 40,000 slides of marine microfossils in the main rock and core collections, and about 10,000 samples of rocks and fossils in the teaching collection. The geological collections at SIO are one of the oldest and largest collections of marine geological samples in the US. The samples in the collections are accessed by oceanographers worldwide who are studying various fields, including geology, geochemistry, geobiology, paleoceanography, geophysics, and more, making the collections a vital part of many interdisciplinary projects. Our core, microfossil and teaching collections are housed at SIO’s campus and our dredged rock collection is housed off-campus at Camp Elliott. Our collections are continually growing as researchers are constantly acquiring new geological samples to study.