The panga journey from San Carlos to El Castillo — typically three to four hours — is one of the most memorable river trips in Central America. The Río San Juan is wide and slow here, winding through dense tropical forest with occasional clearings where small farms appear briefly and vanish again. You share the water with egrets, kingfishers, caimans basking on muddy banks, and the occasional river otter.
There is no road alternative. The only way in or out is by water, and that enforced slowness is part of what makes the Río San Juan corridor feel so different from the rest of Nicaragua. Pangas run from San Carlos several times daily; the schedule is approximate. The journey downstream (San Carlos to El Castillo) is faster than the return trip upstream — allow extra time for the return. Express boats exist but the slower regular service gives better wildlife-watching.