That would be the Colorado river. I did a trip like that two summers ago (on rafts rather than kayaks), and there's (essentially) no communication with the outs

That would be the Colorado river. I did a trip like that two summers ago (on rafts rather than kayaks), and there's (essentially) no communication with the outside world. I did think about how I would react if there were some major world event, but I can only imagine what it feels like for them.