The northern cays form one of Cuba’s newest major tourist resorts, set on a network of small islets leading up to the much larger Cayo Santa María, almost 15km in length. The drive down the 48km causeway from just outside Caibarién to the islands is quite spectacular, and is half the fun of a visit. The dark, deeper waters nearer the land give way to shallow turquoise around the cays, then become almost clear as the network of islets increases in number and complexity. The sea is dotted with mangrove colonies, while herons and cormorants swoop overhead and the occasional iguana basks in the sun on the hot tarmac. The solid rock causeway is broken up by around fifty small bridges, which allow the currents to flow through and provide drivers with distance markers; development on the cays begins just after bridge 36. Only one of the islands, Cayo Las Brujas, is suitable for day-trippers; the others are mostly the exclusive domain of hotel guests, though you can pay for a day pass (usually around $95CUC), which entitles you to full use of all the facilities.