Carved into the sheer limestone cliffs of Capo Caccia near Alghero, Neptune’s Grotto (Grotta di Nettuno) is one of Italy’s most enchanting marine karst systems. Visitors can access the cave either by sea via regular ferry excursions or by descending the dramatic Escala del Cabirol (Goat’s Staircase), a flight of 654 steps carved into the cliffside offering breathtaking panoramic sea views. Inside, the cave reveals a magical subterranean world filled with colossal stalactites, towering stalagmites, and a vast saltwater lake surrounding a central crystalline column.