Keri Caves are a series of spectacular caves located in the southwestern coast of Zakynthos Island and reachable only by excursion or by private boat. The coastal stretch that extends from Kapo Marathia to the Mizithres rocks is called Keri, hence the name of the numerous caves found in this area of Zakynthos Island. Some caves have an entrance wide enough to swim in, in others it is possible to enter directly by boat. Keri Caves have nothing to envy to the most famous Blue Caves, in fact inside many caves the water takes on a blue color. This phenomenon is caused, in some by the presence of an underwater window, in others by the reflection of sunlight on the limestone walls.