World`s longest underground river in Mexico
Divers exploring a maze of submerged caves in Mexico's Yucatan peninsula have found what may be the world's longest underground river. According to British diver Stephen Bogaerts who made the discovery with his German colleague Robbie Schmittner, the waterway twists and turns for 154 km through the region's limestone caverns and stretches between two other cave systems in region: Sac Actun and Nohoch Nah Chich. The peninsula is made of limestone, which allows rainwater to carve out underground passages as it courses towards the Caribbean Sea. Divers' groups are concerned that tourism and rapid development, could endanger the network of systems.