CURACAO (population 170,000), the largest of the ABC islands, and the administrative centre of the Netherlands Antilles, remains relatively unknown outside of Holland and the Caribbean. Originally discovered by the Spaniards in 1499 and taken over by the Dutch in 1634, Curacao has been slower to develop the kind of tourist industry its neighbours are famed for, though its capital city - and recently designated UNESCO World Heritage Site - Willemstad , rivals any in the Caribbean for picturesque charm. The island also offers decent diving and swimming possibilities, especially on the leeward side, with its secluded coves. More active pursuits can be had in the rugged and hilly interior: Christoffel National Park , in the north, is overgrown with towering cacti, scrubby vegetation and gnarled divi divi trees, well worthy of a hike around it. Besides such flora, island inhabitants include goats, bats, lizards, iguanas and countless species of colourful birds. The various plantation houses that dot the island are remnants from Curacao's history as the Caribbean's busiest slave depot in the seventeenth century; the trade was finally abolished here in 1863.