Rugged types should head to Reserva Biológica Bilsa. Crashing waterfalls and spectacular wildlife adorn this biological station. Set in the Montañas de Mache (a small range of mountains), the reserve spans 100ha (247 acres) and is administered by Fundación Jatun Sacha. Biodiversity is exceptionally high in these last vestiges of tropical wet forest. Visitors may see howler monkeys and endangered birds such as the long wattled umbrella bird.

This trip is not for the feeble or the frail: January to June requires hiking or mule-riding a mud-splattered 25km (15.5mi) trail. Contact Jatun Sacha for reservations and volunteer or research information.