From Lake Nicaragua to the Atlantic runs the winding San Juan river; it's like a canal into the country's interior which impressed Louis Napoleon Bonaparte, who referred to this area as the "Constantinople of the New World". It's so well located strategically that a Spanish fort was created in order to stop pirate raids. This fort was of great interest and the scene of bloody battles known as El Castilo. Like the place named after it. What this place lacks, they make up for in kindness. You will not need anything else, not streets or roads (of course, there are issues of accommodation so you should be prepared).