option for some expeditions/projects. A second expedition led by Andrew Regan and Andrew Moon departed in November 2010. The Moon-Regan Trans Antarctic Expedition this time traversed the entire continent twice, using two six-wheel-drive vehicles and a Concept Ice Vehicle designed by Lotus. This time the team used the expedition to raise awareness about the global environmental importance of the Antarctic region and to show that biofuel can be a viable and environmentally friendly option. Water transport Antarctica's only harbour is at McMurdo Station. Most coastal stations have offshore anchorages, and supplies are transferred from ship to shore by small boats, barges, and helicopters. A few stations have a basic wharf facility. All ships at port are subject to inspection in accordance with Article 7, Antarctic Treaty. Offshore anchorage is sparse and intermittent, but poses no problem to sailboats designed for the ice, typically with lifting keels and long shorelines. McMurdo Station (), Palmer Station (); government use only except by permit (see Permit Office under "Legal System"). A number of tour boats, ranging from large motorized vessels to small sailing yachts, visit the Antarctic Peninsula during the summer months (January–March). Most are based in Ushuaia, Argentina. Air transport Transport in Antarctica takes place by air, using fixed-wing aircraft and helicopters. Runways and helicopter pads have to be kept snow-free to ensure safe take off and landing conditions. Antarctica has 20 airports, but there are no developed public-access airports or landing facilities. Thirty stations, operated by 16 national governments party to the Antarctic Treaty, have landing facilities for either helicopters and/or fixed-wing aircraft; commercial enterprises operate two additional air facilities. Helicopter pads are available at 27 stations; runways at 15 locations are gravel, sea-ice, blue-ice, or compacted snow suitable for landing wheeled, fixed-wing aircraft; of these, one is greater than in length, six are between in length, three are between in length, three are less than in length, and two are of unknown length; snow surface skiways, limited to use by ski-equipped, fixed-wing aircraft, are available at another 15 locations; of these, four are greater than 3 km in length, three are between 2 km and 3 km in length, two are between 1 km and 2 km in length, two are less than 1 km in length, and data is unavailable for the remaining four. Antarctic airports are subject to severe restrictions and limitations resulting from extreme seasonal and geographic