Colonia del Sacramento or Paraty?

Colonia's beaches are on the Río de la Plata, a huge estuary, not the sea. The sand is pleasant and the water reaches bathwater warmth in high summer, but it is brown with silt, has no waves and can be closed to swimmers by algae in hot spells. Most people go to these beaches for the sunsets rather than the swim.

Paraty's town beaches are no better, but the bay is a different world. Schooners stop at small forest-backed coves with calm green water, and Trindade, about forty minutes south, adds open-sea beaches and the still, clear pool at Cachadaço. For anyone who plans their days around swimming, Paraty is far ahead.

Both towns have a narrow choice, with plenty of cooking aimed at visitors, but Paraty offers a little more. Its kitchen comes from the sea: grilled fish, shrimp and the banana-tinted azul marinho stew. Some of the candlelit townhouse restaurants are genuinely ambitious, and you can visit cachaça distilleries in the hills.

Colonia sticks to Uruguayan beef from the parrilla, chivitos and dulce de leche. Its strong point is the wine, Tannat and other reds from around Carmelo, best drunk at a courtyard table with the river in view.

The two are well matched. Both are small UNESCO-listed colonial towns that you take in on foot in an unhurried day. The difference is in the story they tell.

Colonia is a frontier town, fought over by Portugal and Spain from 1680, and its lanes, town gate and walls show that mixed past. A cluster of small museums, the lighthouse view and the Moorish-style bullring at Real de San Carlos give it more individual sights. Paraty is a Brazilian gold port of whitewashed houses with coloured frames, baroque churches led by Santa Rita, and a hilltop fort. Its listing takes in the forest and bay around it, so the setting matters as much as the buildings.

Neither town has clubs, but Paraty has more of an evening. After dinner come caipirinhas in bars with a guitarist, the old town stays busy late on weekends and in season, and Trindade draws a young crowd to its beach parties.

In Colonia, a sunset dinner and a bottle of wine are the whole evening. A few wine bars and pubs stay open, but the town is asleep early, and anyone wanting a real night out takes the ferry to Buenos Aires.

This is where the two differ most. Colonia's landscape is flat: the wide brown river on one side and cattle pasture on the other. The riverside rambla is good for walking or cycling at sunset, and there is little beyond it.

At Paraty the Serra do Mar drops straight into the sea. Rainforest climbs into the Serra da Bocaina national park, with stretches of the cobbled Gold Trail, waterfalls and a natural rock slide. In front, the island-dotted bay is made for kayaking and snorkelling, and Saco do Mamanguá, a fjord-like inlet, has a steep hike up to its viewpoint.

Colonia has the better outings, mainly because of one exceptional trip. A fast ferry reaches Buenos Aires in about an hour, with border checks done once at the terminal, so a day in a major capital is easy. Closer to home are the family wineries around Carmelo, the Swiss-settler cheese town of Nueva Helvecia and the British-built core of Conchillas.

Paraty is somewhere to stay put. Trindade is the easy trip, and Cunha's pottery studios and the beach town of Ubatuba are each over an hour away. Ilha Grande needs a night of its own, and Rio and São Paulo are too far for a day.

Both work fairly well with children, though neither has a zoo, an aquarium or anything else built for them, and both have old-town paving that defeats pushchairs. The difference is the kind of day.

Colonia is calm and small. Riding golf carts or bikes along the river, paddling in the shallows and climbing the lighthouse fill a short, gentle stay. Paraty gives older children more adventure: boat days with swimming stops, rock pools at Trindade and the waterfall slide. You have to plan around its heat and summer downpours.

Colonia is the simpler place to manage. The ferry terminal and bus station are a few minutes' walk from the old town, and the flat riverside road makes it easy to reach the beaches and Real de San Carlos by hired bike, scooter or golf cart. Only the wineries and towns further out need a car or a tour.

Paraty's car-free centre is small, but the big rounded stones make walking slow, and the lowest streets flood at spring tides. Beaches are reached by boat from the quay, and the waterfalls, distilleries and Mamanguá landing need a taxi, a hired car or a tour. Getting there usually means a long bus ride from Rio or São Paulo.

Paraty is the better place for a browse. Art galleries, linen boutiques and handmade jewellery fill colonial shopfronts, and hand-labelled cachaça, indigenous basketry and painted wooden boats make good things to take home. It works well as an evening stroll.

Colonia's shops are mostly crafts and souvenirs: leather goods, mate gourds with silver bombillas, wool knitwear and a few antique shops. It is the place to buy a mate set, not much more. Neither town has fashion or department stores.

Paraty is the cheaper of the two for most visitors from Europe or North America. Shared schooner trips, local buses, beach kiosks and simple fish restaurants keep daily costs moderate, but rooms rise sharply over Carnival, New Year and festival weekends.

Colonia reflects Uruguay's high costs for the region. The old town's boutique hotels and restaurants charge about what a Southern European resort would. The good local wine and the mostly free sights soften the bill, and so does staying a few streets out.

In both towns the music mostly comes with dinner rather than from a stage. In Colonia that means the odd tango or candombe number at a restaurant, and mainly in summer. Its one small venue, inside an old fortification by the water, puts on a play or a concert now and then. For opera or a full tango show, people spend the evening in Buenos Aires.

Paraty has more live music, more often. Samba and bossa nova come out of the old town's dining rooms on most evenings, and the town has a long puppet-theatre tradition with nothing like it in Colonia. Festivals bring concerts and performers into the streets. The famous literary festival is talks rather than shows, though, and between festival dates there is still no regular stage programme.

The two are much alike here. Neither has a bathing or spa tradition of its own, and both are restful because of their pace rather than their treatments.

Colonia's calm comes in the late afternoon when the day-trippers leave, with siestas, river rides and winery stays with pools in the countryside. Paraty is calmer in the quiet season, when you can stay in a garden pousada with a hammock, go to a yoga studio, or retreat to a forest or bayside hideaway and switch off completely.