The PTT  transmits messages to a polar orbiting satellite system called Argos.  Argos currently features 6 satellites that offer global coverage.  The satellites themselves are orbiting approximately 900 km above the earth's surface.  They all pass over the poles with each orbit and they receive the messages from the transmitter (while they are on the horizon) and calculate a location estimate for the source of the transmissions.  In this case, that "source" will be the sea turtles.

With this system the turtles can be tracked anywhere he might go for an indefinite period of time.  The tag being deployed is powered by a combination of primary batteries and solar cells.  It could last for may years, as long as the turtle remains alive and the tag remains intact with the antenna attached.  The unit will not only provide location estimates during the turtles travels but will also provide information about the depths of dives that the turtle undergoes.

TRACKING MAPS COURTESY