The tanker, Paul Buck, arrived last week. The Paul Buck is a Navy vessel that is contracted out. So, the 26 sailors on the ship are not U.S. Navy personnel. They left Washington state in November with a full load of fuel, unloaded it somewhere along the way, then filled up again in Australia, before heading to McMurdo.
The tanker brought 3 different types of fuel to McMurdo – JP8 for the airplanes, diesel, and gasoline.
A tanker only shows up once a year so they have to bring an enough fuel to last an entire year. In the pictures below, notice the difference of how high the tanker sits in the water – when empty versus when full. Before leaving McMurdo, the tanker will be filled with water to lower and stabilize the vessel.