very scenic Fanari coastal road is the famous Katavothres (swallow
holes) an extremely rare geological phenomenon
. . .
. . . It is not known in any other place on Earth!
The seawater flows inland here to enter sinkholes below sea level never to
return again, their depth and magnitude unknown.
On 26th February 1963 Austrian hydro geologists dropped 140kg of uranine, a
intensive green colour, into the Katavothres. The colour arrived at Melissani subterranean
lake and the springs at Karavomilos fourteen days
later, on 12th March 1963. This experiment proved that the opposite sides of
the island were
connected by an underground system.
Kefalonia is surrounded by water, so that when the underground cave system becomes
full no more seawater at Katavothres should be able to enter the system. This
does not happen, as the Sami side forms a spring.
The simplified explanation is that salt water is heavier than fresh
water (rain), brackish
water (a mixture of fresh and seawater) is lighter than sea
heavier than fresh water. (See the map below).
The cave system contains salt water at the Argosotoli end and brackish water
at the Sami end, so the water level is below sea level at Argostoli and above
sea level at Sami. The difference is about one meter on both sides.
When the water level in the system rises, the water level of the spring rises,
and brackish water flows into the sea, removing water from the system.
As the water level at Sami cannot rise above the level of the spring, the water
level at Argosotoli will also stay below sea level. So all in all a third element
is needed in the system, the source of the fresh water, which are the rains falling
on the karstified (limestone) centre of the island.
As long as rain is fed into the cave system, the different height
of water level on both sides remains and water will flow into the Kathavothres,
along the cave system into Melissani
subterranean lake and
springs at Karavomilos.
Water flows from Argostoli to Sami and not vice versa? The reason is the
geography: Argostoli is a peninsula, divided from the main island by the harbour
of Argostoli. The clay, which covers the sea floor seems to be more or less watertight,
as the cave system is not filled with seawater in the area of the harbour. Also no rainwater has a possibility to reach this part of the
cave system. This part is always filled with pure salt water, while the rest
of the system
is filled with brackish water.
In the early 20th century, there was a hydroelectric plant and ice factory, which
made use of the force of this water. Unfortunately it is now derelict, with the
old waterwheel left to rust, however it is still a very pleasant area to visit
especially in the evening . . .
. . .
the views overlooking the Gulf of Argostoli are wonderful.
my return visit to Katavothres in 2010, I was very
pleased to find that the whole area including the
wheel has been restored. There is a new waterwheel and the sea is still flowing into the