You must cite data sets just as you would any other referenced material that is not your own, original work.
The 2014 Joint Declaration of Data Citation Principles provides the key principles for using data and supplementary materials within a scholarly work.
There are many citation styles so always consult the preferred style for your NPS Department, publisher, or professional society.
Lastname, Firstname Initials of Author(s)/Creator(s)/Principal Investigator. Title of the data set. Date/data version. Source database: Publisher/Institution. Date accessed/retrieved by you. URL/DOI of data set.
Jurgensen, Sean M. The rotated speeded-up robust features algorithm (R-SURF): supplementary data set. June 2014. Calhoun, Naval Postgraduate School. Accessed: 3 September 2014. URL: http://hdl.handle.net/10945/42653
Solow, Andrew R.; Beet, Andrew R.; Roll, Uri; and Stone, Lewi. Testing for a shift in a species boundary. December 2013. WHOAS, Woods Hole Oceanographic Institution. Accessed: 4 September 2014. URL: http://hdl.handle.net/1912/6348; DOI: 10.1575/1912/6348.