Neptune's Grotto is a stunning natural wonder at the base of the towering Capo Caccia cliff. This majestic sea cave extends several kilometers underground and houses millions-year-old stalactites and stalagmites plus a crystal-clear internal lake called Lamarmora Lake. Accessible via 654 steps carved into the cliff (Escala del Cabirol) or by boat from Alghero. The view from the sea is equally impressive as the cave itself.