A pongo is a term used in the Peruvian Spanish dialect for 'canyon'. It is derived from either Quechuapuncu or the Aymaraponco, meaning 'door' or 'gate.'[1]
See:
The Pongo de Manseriche: a gorge in northwest Peru where the Marañón River runs. The Marañón River has 35 miles of pongo before it joins the Amazon River.[2]