Speleological Shaft “Germaniko”

Location

At an altitude of 106 meters northeast of Lake Vouliagmeni and very close to the residential area, we encounter the “Germaniko” speleological shaft, one of the deepest and most interesting caves of Mount Hymettus.
The entrance to the shaft, hidden from the public eye, consists of two elliptical cavities with diameters of 0.7m and 0.6m, respectively, spaced 0.5m apart. These are located 350 meters from the lake and 500 meters from the coastal shores of the area.

History

In the spring of 1976, the local community of Vouliagmeni informed the Hellenic Speleological Society (E.S.E.) about a shaft presence near Lake Vouliagmeni (Cave Registration No. 6516). This attracted considerable interest, and the speleological community of the time promptly mobilized.
The first exploratory investigation was assigned to Lazaros Chatzilazaridis, who discovered that the shaft was of great interest and required further research due to its speleothems (cave formations) and, mainly, the presence of brackish water at a depth of 95 meters.
The E.S.E. informed the Vouliagmeni community about the shaft’s significance, and following a proposal, the community funded its full exploration. The first major expedition took place in March 1977, involving rotating members of the E.S.E., including Ioannis Ioannou, Dimitris Liagkos, Nikos Leloudas, Giorgos Panagiotidis, Manolis Pavlidis, Giorgos Avagianos, Dionysis Alfieris, Vasilis Pantousis, and Lazaros Chatzilazaridis.

Description

After a descent of 9 meters using ropes, the floor of the first chamber is revealed. It is sloped and scattered with rocks. The chamber is 10 meters long, with a width varying between 2-4 meters, containing large, ancient stalactites, which have unfortunately been damaged by human intervention.
The chamber’s ceiling height varies from 4 to 10 meters, with dome-shaped recesses observed in some areas. A portion of the space is illuminated by daylight entering through the entrance holes.
At the northwest edge of the chamber, the shaft continues vertically downward through narrow passages in the limestone, making the descent quite arduous. This section of the shaft measures approximately 15 meters.
After passing through the narrow passages, the second large chamber of the shaft opens up, with a descent of 12 meters and a diameter ranging from 4 to 6 meters. This chamber is adorned with impressive, large stalactites, and its floor is also sloped.
At the eastern edge, through a small passage, the shaft continues downward to a third large chamber, with a total descent of 22 meters and a diameter of 2 to 7 meters. This chamber also features impressive, large stalactites.
At the base of the third chamber to the east, there is a small, unremarkable room 4 meters long. On the western edge of the third chamber’s floor, there is a relatively narrow and highly sloped passage about 5 meters long. After passing through this, one gets the impression of a “chasm” below, constituting the fourth and final large chamber, which ends at the level of brackish water.
The total descent to the water level in the fourth chamber is 32 meters. As one descends, the diameter of this chamber increases. Specifically, the fourth chamber has the shape of a truncated cone, with the upper base having a diameter of 3 meters and the lower base, where the water is, measuring 12 meters.
About 12 meters above the water level, there are two ledges, east and west of the fourth chamber, connected to the walls, with passages behind them that descend toward the water’s surface.
The water is clear, and brackish, and maintains a consistently high temperature of 27°C, influenced by the volcanic arc of the Aegean, particularly the area spanning Susaki, Aegina, and Methana.
The morphology of the underwater section is abyssal, with a maximum depth of 61 meters, without any further continuation or connection to the Vouliagmeni Cave, as was once speculated.

Geological Observations

The karstic conduit shows heavily eroded surfaces, likely formed by the forceful passage of water. The walls and the boulders throughout the shaft give the impression of a space shaped by an underground river. Given the vertical nature of the shaft, it can be characterized as an ancient sinkhole.
It is likely that the hill’s summit, where the shaft entrance is located today, was once the lowest point of a level surface on Mount Hymettus, from which water drained through the sinkhole during an earlier geological period.
Subsequent geological and geomorphological changes shaped the region into its current form. Once the shaft ceased functioning as a sinkhole and water stopped flowing through it, the stalactites and stalagmites began to form.

Expeditions

The presence of water at the shaft’s greatest depth has always intrigued speleologists due to the potential connection it might have with the complex geological system of Lake Vouliagmeni.
The first dives by Greek cave divers occurred in 1989, conducted by members of the Hellenic Speleological Exploration Club (SP.EL.E.O.), who reached a depth of 30 meters.
In 2008, an exploration of the lake was carried out by the clubs “Nature Lovers, Mountaineers, Speleologists” (F.O.S.) and the Hellenic Speleological Sports Association (S.EL.A.S.).
In March 2011, F.O.S. organized another expedition, with participation from members of SP.EL.E.O., aiming to address questions that had remained unanswered since the 2008 S.EL.A.S. – F.O.S. expedition.
Twenty speleologists took part in this mission, with three (Giannis Protopappas, Giorgos Triantafyllou, and Giorgos Vandoros) diving and confirming the maximum depth of -61 meters, as well as establishing with certainty that the cave has no further continuation.
Finally, in 2012, SPELEO organized a new mission that confirmed the latest findings, effectively concluding the exploration of this unique karstic system.
This speleological shaft remains a popular destination for speleological clubs, and frequent visits are organized throughout the year.

Acknowledgments

On 04/12/2022, we visited the “Germaniko” shaft, reaching the maximum depth of -95 meters, just above the cave’s underwater section, with the Hellenic Speleological Sports Association (S.EL.A.S.) club members.
We extend our gratitude to Nikos Mitsakis and former club members Pavlos Graviotis and Stavros Ladenis for organizing and safely conducting the expedition.
Participants in this activity included Nikos Mitsakis, Pavlos Graviotis, Stavros Ladenis, Evangelos Mitsakis, Konstantinos Pavlakis, Maria Chalkiadaki, Nikolas Margaritis, and Andreas Andrikopoulos.

Research and text editing: Andreas Andrikopoulos
Photos: Konstantinos Pavlakis, Maria Chalkiadaki, Andreas Andrikopoulos, Nikolas Margaritis