River cruising in South America comes down to one river: the Amazon, the world’s mightiest waterway. While the Nile is slightly longer, the Amazon carries a greater volume of water, draining about 20 per cent of the world’s fresh water. It’s on a scale above that of any other waterway. The Amazon’s mouth is more than 300 kilometres wide and nowhere along its entire length is it narrow enough to be spanned by a bridge. The lower reaches are so broad, they’re navigable by ocean cruise ships and it’s too wide to see the shores from midstream.

The upper reaches of the Amazon and its tributaries in Peru, Bolivia and Brazil are the domain of most Amazon river-cruise vessels. Here, the rainforest rules and the superlatives keep flowing: justifiably so, as you’re cruising past what is the richest accumulation of plants and animals in the world. Excursions off the boat may lead to encounters with anacondas or swimming with piranhas (while your guide explains that they aren’t so savage but just get bad press).