Mamoré River
The Madeira river rises more than during the rainy season, and ocean vessels may ascend it to the Falls of San Antonio, near Porto Velho, Brazil, above its mouth; but in the dry months, from June to November, it is only navigable for the same distance for craft drawing about of water. The Madeira-Mamoré Railroad runs in a loop around the unnavigable section to Guajará-Mirim on the Mamoré River, but is not functional, limiting shipping from the Atlantic at Porto Velho.