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Monday, March 8, 2010

Trimix Territory: Emergence de Ressel

With thousands of known caves, France is one of the premier cave diving areas in the world. If a region stands out, it is an area between the rivers of Lot and Dordogne in the southwest of France. The upper valley of the Dordogne is a series of deep gorges. The cliffs, steep banks, fast flowing water and high bridges attract both tourists and divers. In several places the river is dammed to form long, deep lakes. Camp sites and holiday homes have proliferated wherever the valley floor is wide enough to accommodate them. The Dordogne is one of a few rivers in the world that exhibits a phenomenon known as "tidal bore," referring to waves that travel upriver against the current.

Divers will find a multitude of long and deep caves in the area that offer good visibility (usually between 33 feet/10 meters and 99 feet/30 meters). The water temperature is around 55 degrees (13 degrees centigrade) for most of theyear. One of the more challenging dive sites with lots of cave diving history is the Emergence de Ressel, which provides a range of experiences for divers of different experience levels. (Check the link for maps, surveys and more detailed info)

At first sight the resurgence pool looks a bit cloudy, but the change to clear water at depth is startling. Descending in the head pool brings divers to an oval tunnel that disappears in the dark behind the reach of any HID light. After 328 feet/100 meters, the line goes through a minor restriction and the tunnel branches off at the 656 feet/200 meter mark. Both ways lead to the first sump. The upper tunnels remains shallow and reaches a shaft after another 130 feet/40 meters or so, while the lower tunnel descents to the 66 feet/20 meters mark before reaching the shaft. Both tunnels connect through two side-tunnels, but some areas don’t have guidelines, so attention must be paid.

At a penetration of 1,247 feet/380 meters, a big room is reached. Continuing on, a chimney at the 1,312 feet/400 meter mark descends to 164 feet/50 meters. Following the line, a water filled room descends to the 197 feet/60 meter mark at the bottom. Divers have to negotiate several areas with boulders, while the tunnel descends slowly to the 197 feet/60 meter mark. At a penetration of 2,953 feet/900 meters, the cave seems to end. The tunnel leads to the left and up to the 164 feet/50 meter mark again.



However, after ascending divers can see that the main line continues. At a penetration of almost 3,940 feet/1,200 meters, they will encounter a restriction at a depth of 197 feet/60 meters. After negotiating the debris-field, depth increases continuously until divers reach the 263 feet/80 meter mark. At this point, divers have explored approximately 4,921 feet/1,500 meters of cave tunnel.

From here on, the passage ascends again, first almost vertical until a depth of 164 feet/50 meter is reached, and then more slowly. At a penetration of 5,742 feet/1,750 meters and a depth of 59 feet/18 meters, divers reach the point where German explorer Jochen Hasenmayer’s called the dive. Staying left, divers can exit the system and emerge in a small lake after traveling another 656 feet/200 meters.

Hasenmayer reached the 5,742 feet/ 1,750 meter mark in 1981, though it was left to the Swiss cave diver Olivier Isler to make the "breakthrough" 6,398 feet/1,950 meters. British cave diver Martyn Farr has produced 2 books about the caves in this area, and he covers the Emergence de Ressel as well.

The best time for cave diving is the summer season since low rain fall usually leads to low water levels and hence good underwater visibility. Gas fills are available in the picturesque town of Gramat at the "Station de Gonflage", (http://www.gonflage.com/); phone in France is 05653-87536 (international callers have to dial 0033 first). The nearest shop that sells or rents equipment is in Bordeaux - a two hour drive from Gramat (centrally located in the Department du Lot).

While in France, divers should also take the time to explore the local cousin including some of the excellent Bordeaux wines produced nearby, and visit top-side attractions including more than 1,500 castles that dot the Dordogne region. Campsites provide cheap accommodation close to the caves; however, many locals rent out rooms Bed & Breakfast style and offer coffee late and croissants in the morning at similar prices. While the language can be a barrier (most French prefer to speak French only), the hospitality encountered usually makes up for any shortcomings and a bright smile is always the best way to communicate, regardless of language spoken.

Take a virtual plunge into this cave by clicking the picture below.