San José Caves feature the longest navigable underground river in Europe, offering boat tours through stunning caverns adorned with intricate rock formations like stalactites and stalagmites. They are part of the Sierra de Espadán Natural Park in Spain’s Valencian Community.

Peñíscola (optional) is a captivating coastal town in Castellón, within the Valencian Community of Spain. It’s renowned for its majestic medieval castle set on a rocky headland overlooking the Mediterranean Sea. The town also boasts a charming old quarter within castle walls and beautiful beaches attracting sun-seekers and history enthusiasts alike.