Geographically, Puerto Rico is a Caribbean hub, presiding squarely over the waters between Hispaniola and the Virgin Islands. As a commonwealth of the US, however, it remains a world apart from its island neighbours, over a distance that can be measured not just in kilometres, but in dollars. It's island life with infrastructure, the likes of which the Tropic of Cancer seldom sees: excellent interstate highways, for example, allow travellers to zip from coral reef to five-star restaurant, and hikers can traipse through the spectacular El Yunque rainforest on well-paved trails maintained by the US National Forest Service. American influence is strongest in San Juan, where even the ramparts of El Morro – which staved off European aggressors for 500 years – haven't managed to prevent the influx of big-name American fast-food and retail chains. But the capital retains a distinctly Latin character at its core, with Old San Juan hosting a treasure-trove of pastel Spanish colonial architecture on exquisitely restored cobblestoned streets.

Despite the threat of overdevelopment from US dollars, most of the 35-by-100-mile island has managed to elude despoilment. Even in the crowded capital, it's hard to find a sullied beach, and outside the major cities nature is largely untouched – especially in the jungly, mountainous interior; on the relatively hidden beaches along the southwest coast; and on the offshore islands. In fact, the rich natural resources and wide range of hiking, birding, diving and caving opportunities make Puerto Rico as much a magnet for eco-tourists as for sun-worshippers.