Scripps Institute of Oceanography (SIO) Explorer includes five federated collections: SIO Cruises, SIO Historic Photographs, the Seamounts, Marine Geological Samples, and the Educator’s Collection, all part of the US National Science Digital Library (NSDL). Each collection represents a unique resource of irreplaceable scientific research. The effort is collaboration among researchers at Scripps, computer scientists from the San Diego Supercomputer Center (SDSC), and archivists and librarians from the UCSD Libraries. In 2005 SIOExplorer was extended to the Woods Hole Oceanographic Institution with the Multi-Institution Scalable Digital Archiving project, funded through the joint NSF/Library of Congress digital archiving and preservation program, creating a harvesting methodology and a prototype collection of cruises, Alvin submersible dives and Jason ROV lowerings.