Arecibo is one of the most budget-friendly destinations on Puerto Rico's northern coast precisely because its main draws are outdoor and largely free: the iconic Faro de Arecibo lighthouse, the karst headlands of Cueva del Indio, and the protected mangrove and forest reserves are walk-up, no-ticket experiences. The few paid anchors (Arecibo Observatory's converted learning center, guided kayak trips, guided cave tours) can be rationed to one paid activity per day without losing the trip's character.
Cost discipline in Arecibo comes down to three levers: where you sleep (vacation rentals and guesthouses beat the few chain hotels by 30–50%), how you eat (panaderías for breakfast, kioskos for lunch, and family-run chinchorros for dinner), and whether you rent a car (worth it only if you stay inland or plan to chain rural sites). The compact historic center is walkable, and the coast road links most anchors in a single half-day loop.