The hydrocarbon potential of the fore arc basins between the Siberut, Nias, and Simeulue islands and Sumatra was investigated in 2006 by the German Federal Geological Survey (BGR) with marine-geophysical and marine-geological techniques (cruises SO-189--1 and SO-189--2). The basin sediments are relatively coarse grained (in part, of volcanic origin). In most locations, they are too hard for the use of conventional heat flow probes, which penetrate only muddy to soft seafloor sediments.