Rockhopper Exploration, the firm hunting for oil off the coast of the Falkland Islands, has drilled a third "appraisal well" on the so-called Sea Lion feature on the south Atlantic sea bed.Rockhopper has attracted significant attention in the past year after claiming it had discovered "commercially viable" levels of oil in its 100% owned exploration area.It will be at least 38 days before we discover the results of the latest drilling effort but investors are clearly wary of Rockhopper's claims, with the share price down 1.1% in early trading today and 15% on the month.BS