Deep-sea survey for oil is to be conducted through a joint venture between an American firm - Western Geophysical of Houston - and state-owned Tanzania Petroleum Development Corporation (TPDC). The US firm brought in specialised vessel, mv Explora, last week to conduct the survey, the first ever to be conducted outside the continental shelf off mainland Tanzania. The survey aims at obtaining geophysical data that will shed light on the possibilities of striking oil offshore of Tanzania. The country has previously struck natural gas at Songo Songo Island, 230 km south-east of Dar-es-Salaam in the Indian Ocean, and a Canadian joint venture, Songas Ltd, has embarked on building a natural gas pipeline to Dar-es-Salaam.