El Castillo is a remote river town on Nicaragua's San Juan River, accessible only by boat — no roads lead in or out. Perched on a hill above the town stands a Spanish colonial fortress built in 1673, constructed to defend the colonial capital of Granada from pirate incursions navigating upriver from the Caribbean. The settlement retains much of its historic character, with the hilltop fortification offering sweeping views of the surrounding jungle and river. Gates arrived here during his search for Cornelius Vanderbilt's lost steamship, the Orus, when the team pulled in to refuel. As Gates noted on camera, the town looks like "a lost set from the jungle cruise" — and in many ways, not much has changed since the mid-19th century, when steamship passengers bound for California's gold fields walked these same streets.
Spanish colonial fortress constructed at El Castillo to protect Granada from pirate attacks via the San Juan River
A young British naval officer, Horatio Nelson, captured the fort during a British military campaign in the region
El Castillo became a major stop on Cornelius Vanderbilt's Accessory Transit Route; passengers disembarked here to bypass the river's most difficult rapids, with a rail system built to haul cargo and travelers around the section
Gates and his team stopped at El Castillo during the Expedition Unknown S16E06 investigation into Vanderbilt's lost steamship, the Orus
El Castillo's fortress — formally known as the Fortaleza de la Inmaculada Concepción — was built by the Spanish in 1673 at a strategically critical bend in the San Juan River, where the rapids made river travel difficult and enemy ships vulnerable. Its position was no accident: Granada, the wealthy colonial capital deep inland on Lake Nicaragua, depended on controlling this chokepoint to survive pirate raids. As Gates learned on camera, the fort was designed precisely to stop Caribbean-based raiders from pushing upriver.
The fortress is also tied to one of Britain's most famous naval figures. A young Horatio Nelson, long before his victory at Trafalgar, led an assault on the fort around 1780 during a British attempt to sever Spanish colonial communications across Central America. Nelson's campaign ultimately failed due to tropical disease ravaging his troops, but the episode cemented the fort's place in broader Atlantic history — a detail Gates' companion noted on camera while surveying the view from the battlements.
By the mid-19th century, El Castillo had reinvented itself as a transit hub. When Cornelius Vanderbilt launched his Accessory Transit Company in the early 1850s to ferry gold rush passengers across Nicaragua, the rapids near El Castillo posed a serious logistical problem. According to what Gates was told on site, the rapids were so formidable after the Orus disaster that Vanderbilt's operators gave up on pushing steamships through entirely, instead building a short rail portage system to carry passengers and cargo overland around the castle before loading them onto a second vessel downstream.
Gates' S16E06 stop at El Castillo was a fuel break and historical detour rather than an excavation, and the episode makes no claim of new discoveries here. What it does offer is a vivid on-the-ground sense of how isolated and unchanged the town remains — and how a crumbling Spanish fortress on a jungle hilltop once sat at the intersection of colonial defense, British imperial ambition, and American Gilded Age commerce.
El Castillo has no road access — the only way in or out is by boat along the San Juan River, keeping the town remarkably isolated from modern development.
The hilltop fortress was built in 1673 specifically to guard against pirates raiding Granada via the San Juan River, one of the few water routes connecting the Caribbean to Nicaragua's interior.
Horatio Nelson, later one of Britain's most celebrated admirals, participated in an assault on the fort as a young officer — long before his famous victory at the Battle of Trafalgar in 1805.
During the California Gold Rush era, Vanderbilt's transit company built a small rail portage system at El Castillo so passengers could bypass the rapids entirely and board a second steamship farther downriver.
El Castillo is accessible only by boat along the San Juan River, typically departing from San Carlos at the southern end of Lake Nicaragua. Visitors can explore the town on foot and tour the hilltop fortress, which has been partially restored and generally welcomes visitors. Check current travel advisories for Nicaragua before planning a trip, as conditions can change.
San Carlos, Nicaragua, approximately 70 kilometers upriver — itself a small town, but the primary departure point for boats heading down the San Juan River toward El Castillo.
The dry season, roughly December through April, generally offers more manageable river conditions and less rainfall, making boat travel along the San Juan River more predictable. The wet season brings heavier currents and rain, though the jungle scenery is exceptionally lush.
Tayos Cave
Tayos Cave, like El Castillo, is a remote Central/South American site accessible only through challenging terrain that Gates investigated in connection with historical mysteries and lost discoveries.
Ecuador Cloud Forests
The Ecuador Cloud Forests represent a similar Gates investigation into remote, jungle-covered Latin American terrain where history and geography intersect in ways that are difficult to reach and harder to verify.
Inca Trail
The Inca Trail connects to Gates' broader pattern of following colonial-era and pre-colonial trade and transit routes through Latin America, much as the San Juan River route defined El Castillo's historical importance.
Historical data sourced from Wikipedia