Knocking on Brazil’s back door, Guayaramerín is twinned with the Brazilian town of Guajará-Mirim on the other side of the Río Mamoré. This lively town thrives on all kinds of trade (legal and illegal) with Brazil, and its streets are full of dusty motorcycle tracks and markets heaving with synthetic garments. It is now the northern terminus for river transportation along the Mamoré.
There's not a whole lot to do here except cruise down the river. North of town you can follow la ruta de la goma (the Rubber Trail) to Cachuela Esperanza, an old rubber-boom town that was once the grandest city in the Bolivian Amazon. Little remains of its former opulence, but it's a scenic spot near rapids of the Río Beni.