Darien

Declared in 1980, it is the largest protected area in the whole of Central America and Panama, and a UNESCO World Heritage Site since 1981. Its impenetrable forest makes up the Darién Gap, the only stretch along the whole length of the Pan-American Highway — which otherwise runs almost unbroken from Alaska to Argentina — that has never been paved, leaving a gap of more than 100 km with no road between Panama and Colombia, for reasons both ecological and security-related. In recent years the Darién forest has also become one of the busiest and most dangerous overland migration routes in the world, crossed on foot by hundreds of thousands of people heading north each year.