The breathing wall: the myth of the underground passages
Have you ever walked along the Muralla of Cartagena and felt the ground vibrate? It's not the heat, nor the echo of tourists. It's the city breathing. For as long as I can remember, the people of Cartagena have told stories of secret tunnels that connected the walled city to the sea. Some say pirates used them to escape, others that slaves dug them to move gold unseen. The truth, like almost everything in Cartagena, is buried under centuries of dust and legend.
In May 2026, there are still those who swear they have seen a sealed door in the San Diego sector, right behind a handicraft store. It's not fiction: hidden canals exist, some accessible, others closed by the Institute of Heritage and Culture. But if you know where to look, the Muralla shows you its seams. This article is for those who want to see the walled city as a living organism, not as a postcard.
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What to do: the three canals you can see (and one you can't)
Las Bóvedas: the smugglers' canal
The most obvious and least explored place. Las Bóvedas, those 23 arches that today house jewelry stores and restaurants, were originally military warehouses. But beneath them, at sea level, there is a drainage canal that connects to the bay. Local guides say that boats loaded with goods used to enter through here without paying taxes. Today you can walk along the outer edge, where the water hits the stones, and see the rusty grilles protecting the entrance.
Fun fact: During the 2019 restoration, workers found an 18th-century Spanish seal embedded in one of the floodgates. No one knows why it was there.
The San Diego sector: the door of the Holy Office tunnel
Walking along Calle del Sargento, right where the cobblestone ends and the shadow of the Santo Domingo Church begins, there is a grate on the ground. It's not just any sewer: it's the entrance to a tunnel that, according to the archives of the General Archive of the Indies, connected to the San Agustín convent. Local historians assure that the friars used it to move unseen during the Inquisition era.
You can't go down without permission from the Institute of Heritage, but if you stand on the grate at 5 pm, when the sun hits from the side, you'll see the reflection of stagnant water. It's a reminder that history is not dead, just waiting.
The Baluarte de San Ignacio: the breathing canal
This is my favorite. On the northwestern corner of the Muralla, where the Caribbean wind blows strongest, there is a rotten wooden floodgate. If you lean in, you hear the seawater coming in and out with the waves. It's not a secret tunnel, but a ventilation canal that military engineers designed to keep gunpowder from getting damp. But locals call it "the devil's mouth" because, according to legend, the spirits of slaves who died during construction came out through here.
To see it properly, you have to go with a guide who has the key to the access door. Ask at the tourism office in Plaza de los Coches for the "Shadows and Canals" tour. It leaves on Thursdays at 7 pm, only 8 people per group.
The canal that doesn't exist (but everyone searches for)
There is a recurring myth: a tunnel connecting Castillo de San Felipe with the Palace of the Inquisition. There is no archaeological proof that it exists, but every so often a TikTok video appears of someone claiming to have found it. The reality is that the castle and the palace are separated by more than a kilometer of solid ground, and any tunnel of that length would have collapsed centuries ago. But the myth persists because people want to believe that Cartagena holds secrets that even archaeologists don't know.
Where to eat or drink near the canals
At Las Bóvedas: Café del Mar (but not the one you think)
Everyone knows Café del Mar on the Muralla, but few know that on the ground floor, right where the Las Bóvedas canal begins, there is a natural juice stand called La Juguería de la Abuela. It has no sign, just a 70-year-old lady who sells corozo and green mango with salt juice. If you ask her about the tunnels, she'll tell you the story her grandfather told her, who worked on the construction of the Hotel Santa Clara. It's not a restaurant, it's an experience.
Address: At the pedestrian entrance of Las Bóvedas, left side. Open from 9 am to 6 pm. Juice: $5,000 COP (reference prices from May 2026).
In San Diego: La Cevichería de la Calle del Sargento
A two-minute walk from the tunnel grate, there is a place with red plastic tables that looks improvised. It's called Ceviches del Sargento (not to be confused with the famous La Cevichería in Getsemaní). Here the shrimp ceviche comes with patacón and a chili sauce that burns like the memory of a slave. The owner, Don Carlos, is a former tour guide who knows all the canal routes. If he likes you, he'll show you old photos of when the Muralla had floodgates open to the sea.
Address: Calle del Sargento #8-12. Open Tuesday to Sunday, 12 pm to 9 pm. Ceviche plate: $22,000 COP.
At the Baluarte de San Ignacio: El Bar del Viento
It's not a bar with a name, but an improvised terrace on the top of the bastion. A man named José sets up a styrofoam cooler with cold beers on weekends. There's no sign, just the sound of the waves and the smell of salt. It's the best place to watch the sunset after exploring the canal. Ask for "José's cooler" at the entrance of the bastion.
Hours: Saturdays and Sundays, 4 pm until the beers run out. Beer: $4,000 COP.
How to get there and transportation
The Walled City is walkable, but the canals are scattered. Here are the exact routes:
- For Las Bóvedas: Enter through the Puerta del Reloj, walk straight to Plaza de los Coches, turn left onto Calle de la Moneda until you reach the sea. It's a 10-minute slow walk.
- For San Diego: From Plaza de Santo Domingo, walk north on Calle del Sargento. The grate is halfway down the block, next to a handicraft store with a "Mochilas Wayúu" sign.
- For the Baluarte de San Ignacio: Take Calle de la Factoría from Plaza de la Aduana, walk 15 minutes to the end, where the Muralla meets the sea. There is no signage, but you'll see a green wooden door.
Public transportation: If you're coming from outside the center, take a bus that says "Centro Histórico" from Avenida San Martín. Get off at Plaza de la Aduana. From there, everything is on foot. I don't recommend a taxi because the center has pedestrian streets and traffic is slow.
Recommended tour: The "Shadows and Canals" tour leaves from Plaza de los Coches on Thursdays at 7 pm. It costs $60,000 COP per person (prices from May 2026). Includes a flashlight, bilingual guide, and access to the Baluarte de San Ignacio. Book 24 hours in advance at the tourism office in Plaza de los Coches. Ask for the guide Jorge "el Loco", who is the only one with the key to the floodgate.
Local tips
- Don't go alone: The canals are not dangerous, but some areas are dark and damp. Always go with a local guide who knows the tide schedules. If the water rises, some accesses flood.
- Wear non-slip shoes: The stones of the Muralla are polished by centuries of footsteps and seawater. Flip-flops are a bad idea. Wear sneakers or water shoes.
- Respect the grilles: Some canals are closed for restoration. Do not try to jump the fences. The Institute of Heritage has imposed fines of up to $500,000 COP for those who enter without permission.
- The best time: Between 4 pm and 6 pm, when the light is golden and the heat drops. Also, local guides are usually available at that time.
- Don't believe everything unofficial guides say: In Plaza de los Coches, there are guys offering "secret tours" for $20,000 COP. Most are scams: they take you to an alley and tell you made-up stories. Look for guides with an Institute of Heritage ID card.
- Bring a flashlight: Your cell phone doesn't light up enough to see the details of the canals. A headlamp leaves your hands free to hold onto the walls.
- The little-known fact: In the Las Bóvedas canal, if you lean in at the corner closest to the sea, you'll see a Latin inscription carved into the stone. It says "Aqua et ignis" (water and fire). No one knows exactly what it means, but historians believe it was a mark of the military engineers.
Frequently asked questions
Is it safe to enter the hidden canals?
Yes, as long as you go with an authorized guide and follow the instructions. The accessible canals are in good structural condition, but some areas have slippery stairs and poor ventilation. I do not recommend entering if you have claustrophobia or reduced mobility. Official tours include basic medical insurance.
Can I visit the canals without paying for a tour?
Not all of them. The exteriors of Las Bóvedas and the Baluarte de San Ignacio are public access, but to see the inside of the canal you need permission from the Institute of Heritage. The grate in San Diego is on the street, but you cannot go down without authorization. If you want to save money, go to Las Bóvedas at low tide (check tide tables at the tourism office) and you'll see the canal entrance from the outside.
Are the canals open to the public all year round?
It depends on the weather. In the rainy season (April-June and October-November), some canals are closed due to flood risk. In May 2026, the Baluarte de San Ignacio is open only on Thursdays and Saturdays. Check the current status on the Institute of Heritage website or by asking at the tourism office in Plaza de los Coches. There is no public phone number, but the opening hours are Monday to Friday, 9 am to 5 pm.
Is there a completely secret canal that doesn't appear in guides?
Yes, but I'm not going to tell you here because the locals protect it. It's a small access in the La Matuna sector, behind a bicycle parts store. The neighborhood kids use it to play. If you ask the older neighbors respectfully, they might show you. But don't share it on social media, because if it goes viral, the Institute will seal it.
Historical or contextual introduction
The Muralla de Cartagena, built between the 16th and 18th centuries, is not only a symbol of the city but also a testament to its history marked by defense against pirates and conquistadors. This monumental structure, which surrounds the historic center, is the result of a monumental effort to protect the city, making it a strategic point on the Caribbean trade route. Over the years, the stones of the wall have witnessed countless stories, from the attacks of Francis Drake to the influence of African culture in the region.
A lesser-known aspect of the wall is the hidden canals found beneath its surface. These canals were designed not only for defense but also for rainwater management, demonstrating the ingenious urban planning of the time. Many Cartagena locals still remember their grandparents' stories about these passageways, which were once used for escape or for the trafficking of goods during the colonial period.
Today, exploring the Muralla de Cartagena is more than just a tourist walk; it's an opportunity to connect with the living history of the city. Be sure to visit in the afternoon when the sun sets, as the play of light on the old stones creates a magical atmosphere. It is also advisable to bring a camera, as the views from the bastions are spectacular and tell stories that words cannot express.