Next is a trip to Uruguay – to Colonia del Sacramento, 50 minutes by ferry across the mighty Rio Plata. It’s a twin-hulled catamaran called a Buque Bus – a monster as big as a cross-channel ferry. Disembarking on the other side is like stepping back in time. There are only 20,000 people here. No traffic lights on the main street. A rundown building in need of repair. Sandy beaches with locals enjoying a barbeque. The old town is a tiny cobbled affair surrounded by a dilapidated wall. Seven times it changed ownership since the 1700s as the Spanish and Portuguese constantly fought over its strategic position at the river mouth. Climbing the tiny lighthouse shows why. Our charming hotel is an all-stone building that was previously the fire station, boasting a courtyard with a fountain and overhanging bougainvillea. As night falls, rustic lamps light up to provide the ideal backdrop for dinner in the tiny main square, serenaded by a stream of drummers who thunder past at midnight.
After strolling round a range of artisan shops it was time to move on. Back over the enormous river – rougher this time but bearable – for our third and final stay in Buenos Aires. A superb French meal and a good night’s sleep set us fair for the next stage – a one and a half hour flight to the north of the country to visit the widest waterfalls in the world: Iguazu. As the plane headed north, urban sprawl gave way to farmland and eventually progressively larger rivers, heralding the onset of an increasing body of water.