Cruising the Great Wild Rivers

[genomic]

Been wondering about the viability of motorsailing up a large, wild river such as the Fly river in PNG and the Amazon. On a cruising itinerary that transited the mouth such a behemoth I'd be tempted to turn 90 deg and travel upstream, partly for the experience and partly for the challenge. Not sure how difficult such a thing would be though.

AFAIK small-ish cruise ships do trips up the Fly and Amazon, so navigationally it should be possible, but these vessels may be specifically kitted out to deal with hazards such as submerged floating logs and so forth?

As well, I know there are problems with raskols (criminals) in PNG, and this may be problematic while mooring close to villages, though crime is less prevalent outside of cities.

Does anyone have any experience boating up the Fly, Amazon, or other wild river systems, and what specific hazards and conditions is one likely to encounter that could make life difficult.