The Netherlands Antilles are composed of two Caribbean island groups. Curaçao – the richest and wealthiest island – and Bonaire lie just off the Venezuelan coast, and Saba and St. Eustatius and the Dutch part of St. Martin lie 800 km (500 miles) to the north. Financial scandals, arguments over the federation's future, political instability – particularly on the four smaller islands – and allegations of narcotics-trafficking have strained relations with the Dutch government, the major aid provider. Refining of petroleum at the Curaçao refinery using oil imported from Venezuela is the islands’ principal industrial activity.