As of 2007, the Hawaii Ocean Time-series has made near monthly measurements at Station ALOHA (22° 45'N, 158° 00'W) for the past 19 years. Data from this Eulerian Ocean Observatory have been supplemented by several transects of opportunity to detect spatial variations of key biogeochemical properties, including nutrients (N, P, Si), chlorophyll, DIC/Alkalinity, dissolved & particulate organic matter, pico- & nano-plankton biomass & activity, and bio-optical characteristics to name a few. This HOT transect, from American Samoa to Hawaii (May 2005) provided a comparative analysis of relavent biogeochemical properties between several open ocean provinces including both the North and South subtropical gyres and equatorial waters.