Answer: Saudi Arabia
Freshwater is so abundant in most of the world that it seems bizarre to think of a land that is devoid of rivers. Yet a survey of the globe reveals that there are over a dozen countries with no flowing rivers (or even a dry river bed) to speak of. Some countries, like the Maldives, lack rivers because of their elevation and geographic composition (the Maldivian islands are tiny and flat). Other countries, like Bahrain, are the dry deserts you’d anticipate a riverless country to be.
Among all the riverless countries, the largest one is Saudi Arabia with an area of 830,000 square miles (2,150,000 square kilometers). That’s a pretty vast area to be completely devoid of anything even resembling a river and, in that, you’d be right to guess there is at least a river-like natural structure or two.
While Saudi Arabia does lack permanent rivers, there are temporary bodies of water that fill the bottoms of ancient river valleys known as “wadis”. None of these rivers permanently hold water and most remain dry for the majority of the year, but they do offer a fascinating look at the geological history of the region and a past where the desert wasn’t all-encompassing.