In the northern section of Alta Verapaz, the lush hills drop away steeply onto the plain that marks the frontier with the department of Petén. The terrain is a beguiling mix of dense patches of rainforest, towering tooth-like outcrops of limestone called karsts, and pastureland. Some of the most extensive cave systems in Latin America are located here, particularly in the Candelaria region, which is riddled with caverns. The paved highway runs north from Cobán, passing Parque Hun Nal Ye and Chisec, from where you can explore Bombil Pek cavern and Lagunas de Sepalau, then skirts the ruins of Cancuén. Otherwise it’s dirt tracks all the way, including a branch road that leads to the spectacular, remote lake of Laguna Lachúa.