NOTICE: The project that is the subject of this report was approved by the Governing Board of the National Research Council, whose members are drawn from the councils of the National Academy of Sciences, the National Academy of Engineering, and the Institute of Medicine. The members of the committee responsible for the report were chosen for their special competences and with regard for appropriate balance.

This study was supported by Contract/Grant No. N00014-05-G-0288, TO 17 between the National Academy of Sciences and the Office of Naval Research. Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the views of the organizations or agencies that provided support for the project.

Cover: Images from top to bottom counterclockwise: The image of original R/V Atlantis (1931-1964) was provided by Woods Hole Oceanographic Institution. The 1970 image of R/V Melville was provided by Scripps Institution of Oceanography, UC San Diego Libraries. The image of R/V Alpha Helix (University of Alaska Fairbanks) was provided by Bill Rook. The image of R/V Pelican was provided by Nancy Rabalais of the Louisiana Universities Marine Consortium. The image of R/V Thompson was provided by Kathleen K. Newell of the University of Washington. The image of R/V Kilo Moana was provided by SOEST, the University of Hawaii.