Katavothres are located at the entrance of Argostoli and they were a mystery because the sea water that came at shore would disappear into them. The mystery was solved in 1963 when a team of researchers throw in the water a special coloring substance to track its route. It was proved that the water travels underneath the island and reaches, after a few days, the other side of Kefalonia, at the east, passing even from the Melissani Cave.