Amalfi - Caves Grotta dello smeraldo e presepe subacqueo The haunting cave was named after the spine-chilling emerald colour which emanates from the seawater. Stalactites hang down from its 24 metre-ceiling while stalagmites grow to ten metres tall. Each year, skin-divers from all over the country make their traditional pilgrimage to this ceramic presepe submerged beneath the water.