River stops even with his shoulder, looking out onto the bridge, her hands in her back pockets.

"The vocal text is like a tour guide, speaking about whatever it is you're looking at. The subvocal text, well... The knowledge is simply there. You see a flash of blue and you recognise the Resplendent Quetzal."

She steps out onto the bridge. "We're three hundred feet above the forest floor here, so do be careful of the edge."