Cartagena or San Juan?

In Cartagena you have to take a boat to get the Caribbean you came for. Bocagrande and Castillogrande have darkish sand, water clouded by river sediment and plenty of vendors, so a proper beach day means a boat to Playa Blanca on Barú or the Rosario Islands, which works but takes half the day.

San Juan has good swimming right in the city. Isla Verde's reef-sheltered sand, Ocean Park and the calm bay at Escambrón are minutes from the hotels, and Luquillo's palm-backed crescent is under an hour east. The one catch is the rough water off parts of Condado, which is why locals stick to the lifeguarded balnearios.

Both cities eat well, but the flavours differ. Cartagena cooks like a port, with whole fried fish, coconut rice, ceviche from street carts, arepas de huevo and the coconut sweets of the Portal de los Dulces. A polished layer of restaurants in restored colonial houses sits inside the walls.

San Juan's cooking is heavier and built on plantain and pork: mofongo, alcapurrias at the Piñones kiosks, and the roast-pork stalls of Guavate up in the hills. Rum, mountain-grown coffee and chef-led kitchens in Santurce give it a little more range. In both old towns, many menus are aimed at visitors.

These are two Spanish fortress cities with a lot in common, and either can be seen in two or three days. Cartagena's walled city is the larger and more complete townscape, with about 11km of ramparts to walk and lived-in streets in San Diego and Getsemaní. The hilltop Castillo San Felipe de Barajas is the single most striking building in either city.

San Juan's forts make more of their setting. El Morro faces the harbour mouth from its grassy headland and San Cristóbal looms over the eastern approach. The city is also better for museums: the Museo de Arte de Puerto Rico in Santurce outshines Cartagena's modest Gold Museum and Inquisition palace.

Cartagena's night is a small circuit you can walk. It starts with street food and drummers on the steps of Getsemaní's Plaza de la Trinidad and moves on to salsa bars nearby or rooftop bars inside the walls. Champeta parties, party boats and chivas with a band on board are local specialities, and the touts come with them.

San Juan's going-out is spread across several districts and peaks at the weekend. From Thursday to Saturday, La Placita in Santurce becomes a street party, and Calle San Sebastián mixes dive bars with salsa and reggaeton floors. Condado and Isla Verde add casinos and hotel clubs, and weeknights are much quieter.

This is San Juan's biggest advantage. El Yunque's rainforest, with its tree ferns, waterfalls and lookout towers, is under an hour away, and Laguna Grande near Fajardo glows on night kayak trips. Winter surf on the north coast and the Piñones mangrove boardwalk add more.

Around Cartagena the land is flat, hot and farmed. The outdoors here means snorkelling over the boat-worn reefs of Corales del Rosario, canoeing the mangroves at La Boquilla, kitesurfing in the dry season, and a wallow in the Totumo mud volcano.

From Cartagena there is not much within a day's reach. San Basilio de Palenque, with its own language and music, makes a rewarding half day, but Mompox and Santa Marta are too far to go and come back.

San Juan gives you more. Ponce's colonial plaza and art museum are a drive over the mountains, the ferry to Cataño leads to the rum distillery, and Loíza is the home of bomba. Culebra and Vieques are better with a night's stay.

San Juan is the easier city with children. El Morro's tunnels and kite-flying lawn, calm water at Escambrón and Luquillo, and El Yunque's short paved trails fill several days. English, US-standard pharmacies and supermarkets, and resort pools make the practical side simple.

Cartagena has horse carriages, ramparts and the National Aviary on Barú, and the island beaches are a treat. But the good water is a long boat ride away, the city beaches are crowded with vendors, and the humid heat wears small children out quickly.

Cartagena is much easier to get around. The walled city, San Diego and Getsemaní are a few minutes' walk apart, the Castillo San Felipe is a stroll from Getsemaní, and plentiful cheap taxis cover Bocagrande. The midday heat is the main thing that slows you down.

San Juan spreads along its coast. The Tren Urbano misses both the old town and the beach districts, buses are slow, and El Yunque, Luquillo or Ponce mean a hire car or a tour, with heavy highway traffic at rush hour.

Cartagena is the place for Colombian craft. The vaulted Las Bóvedas sell Wayuu mochilas, sombreros vueltiaos and hammocks, jewellers around the Plaza de Bolívar sell emeralds, and local designers make linen resortwear for the heat.

San Juan leans towards US-style malls, led by the huge Plaza Las Américas, plus a short run of designer boutiques on Ashford Avenue. For things to take home, its old town has carved santos, vejigante masks, cigars, rum and coffee.

Cartagena is clearly cheaper, as long as you stay away from the restored-mansion hotels and smarter old-town restaurants. Getsemaní guesthouses, canteen set lunches, street food and taxis cost little, and island trips are fairly priced if you agree the fare first.

San Juan costs about what a mid-sized city on the US mainland does, with tips and taxes added to restaurant bills. Beachfront rooms are dear in winter, and a hire car adds up. Kiosks and roadside stalls help, and rooms are cheaper in summer and autumn, which is hurricane season.

San Juan has more on stage. The Centro de Bellas Artes in Santurce houses the Puerto Rico Symphony Orchestra and touring theatre, the Casals Festival brings classical music every year, and the Hato Rey arenas host big Latin concerts. Bomba sessions also let visitors join the drumming and dancing.

In Cartagena, the ornate Teatro Adolfo Mejía and the January classical festival in churches and courtyards are the formal highlights. The rest of the year, music means cumbia dancers in the plazas and champeta sound systems.

Neither city has a spa or bathing tradition, and both are loud. In Cartagena, rest means a colonial-house hotel with a plunge pool and shaded courtyard, a cheap massage on the sand, or a few slow nights in a hammock on the islands.

San Juan's version is larger and more resort-based, with hotel spas in Condado and Isla Verde, yoga around the beach districts, and countryside retreats for real quiet.