Guinea-Bissau is one of the world's poorest nations. Farming and fishing are the leading occupations; cashew nuts are the main cash crop, and rice, corn, beans, cassava, and cotton are grown for domestic use. The country's mineral resources, including phosphates, bauxite, granite, and limestone, are largely unexploited; however, prospecting for offshore petroleum deposits has begun. Industrial activity is mostly limited to the processing of agricultural products. Cashew nuts are by far the largest export; fish, seafood, peanuts, palm kernels, and timber are also exported. Imports include foodstuffs, machinery, transportation equipment, and petroleum products. The nation's location and political instabilitiy has also made it a major transshipment point for the illegal drug trade from Latin America to Europe and the Middle East. The main trading partners are India, Italy, Senegal, Nigeria, and Portugal.