South of Cobija between the ríos Tahuamanu and Madre de Dios, almost 7500 square kilometres of some of Bolivia’s most pristine lowland Amazon rainforest are protected, at least on paper, as the Reserva Nacional de Vida Silvestre Amazónica Manuripi. With financial help from Germany, the park’s SERNAP-administered staff have, for several years, been working with the reserve’s scattered campesino communities to promote the sustainable extraction of rubber and Brazil nuts, while improving social and working conditions. While there are plans to develop ecotourism, there’s no real infrastructure in the reserve as yet save for some very basic cabañas; you’ll need to take all your own food and bedding. There are plenty of trails used by the castañeros during the Brazil nut-collecting season (Nov–Feb), however, and at least one specific walking route, a two-hour-plus trek from the tiny community of Curichon to Lago Bay, from where you can continue to Arroyo Malecón, near the Peruvian border. Lago Bay is also accessible via the motorized canoes with which the guards patrol the river in search of illegal loggers. Before setting off you’ll need to give advance notice – ideally a couple of days – to the park office in Cobija.