Good question, but really good series of questions.
Why is there a boat?
There has been an ongoing, international effort to create a single catalog about the World’s Oceans since the early 1990s. This is part of a research endeavor known as CLIVAR which was created in order to study CLImate VARiability and Predictability.
One of the main facets of this project is periodic oceanic transects where along with temperature, salinity, and dissolved oxygen, countless other measurements take place. Various institutions piggyback on the transect (hiring vessels is expensive), and can measure anything from biological productivity to CFCs to sunlight intensity.
Why is it in the South Pacific?
The original plan for this vessel and this cruise was through the Indian Ocean perilously close, and even within the regions frequented by pirates. US Research Vessels are required to be unarmed, so our only defenses would be high powered hoses and thrown projectiles. While an amazing plot to a possible action/comedy, the plan was changed to the South Pacific.
Why are you on it?
There is a website where all the US Research Vessels have to catalogue their yearly plan. This last summer while interning at Woods Hole Oceanographic Institution, I noticed that the Chief Scientist of this particular cruise worked down the hall from me. In the same conversation where I introduced myself, she brought up the cruise and invited me along.
Here is the link to the 2010 Schedules.
They are constantly in need of young people for these vessels, so check it out. At the very least, they pay for flights and a few days at either end of the cruise.