Parque Natural de Urkiola · Ayuntamiento de Abadiño

Potholing in Urkiola

Abaro-Jentilzubi system

Degree of difficulty: Medium-high

Risk: Medium-high

Not recommended during rainy periods

This sytem was initially known as 2 independent cavities, until the GEMA Potholing Group discovered that it was linked in 93. It is a system consisting of various active zones at different levels and inactive or fossil zones of various sizes and volumes. The river comes in through its upper entrance from the Túnel de Abaro, and after going through different areas of the cavity, it comes out again at the Resurgencia de Jentilzubi, situated a little lower in Cueva Jentilzubi I. It is the Park’s best known crossing, as it is an attractive route even though the risk is medium-high, with a wide range of difficulties, from a water zones, sinkholes of different levels, large fossilised galleries and many different types of crawl and tight galleries.

How to get there:

After you leave the Indusi neighbourhood in Dima, go over the bridge across the river and continue along a tarmaced road to a farmstead. Then, continue along a track until you reach a stop sign. You will be able to see the Gibeldar entrance on your left as you go along the path. As soon as you reach the rest place, take the path to your left that will take you to the monumental entrance to the Baltzola cave. Before you reach the cave, you will see the river bed on your right that is flowing from the Abaro Tunnel and flows down the Sima de Abaro.

To reach Jentilzubi I, take the same track from the aforementioned farmstead that will take you to its mouth, which is easily to recognise as it is located to the right of the large rock bridge known as Jentilzubi, which you have to cross to go to Baltzola and the Sima de Abaro.

Description:

Equipment:

2 20-metre ropes for double descent.

Fitted with stainless steel belays.

You must be sure that you can complete the crossing, as once you have gone down the sinkholes, you will have no other option than to continue to Jentilzubi I. The route is therefore only recommended for highly experienced potholers.

The river is seasonal and great care has to be taken in the first sinkhole, as it can be very dangerous when the river is in flood.

Enter through Abaro and go down the first 2 metres until you reach the first joint. You will need to take care to reach it as it is rather hidden. It is a 6-metres sinkhole, that leads on to an channelled zone that is no more than 60 cm wide and you will need to proceed using the handrail. Follow the river bed until you reach a 8-metre sinkhole which the water pours down. Using another handrail, continue to the next 15-metre a sinkhole, a beautiful airy passage where you should stop when you reach a small rock pool, before climbing up the choke opposite.

Climb up the choke and then cross a series of small obstacles that will take you to the Gran Cañón, an impressive gallery that is 50 m long and 20 m wide at some points. At the end of the gallery, you will come across an impressive white flowstone. Climb up the choke until you come to the crawl passage that will take you to a new active zone. It is a slightly complicated area due to the narrow stretches, which may make us become disorientated. In the active zone, you will cross various phreatic tubes and small meanders that may overflow during the rainy period, even though it is not an obstacle to completing the crossing.

The active zone progressively becomes a fossil zone that opens out and you will shortly reach an area of rimstone pools, which are normally flooded. After crossing this zone, you will reach the lower part of this gallery and you climb up a small choke zone located to our right, which will take you through several crawl passages and narrow points to the mouth next to the majestic Jentilzubi.

You can also enter through the Jentilzubi I cave and then follow the route to the bottom of the 15-metre sinkhole, even though it is more difficult to find the passages that will take you to the Gran Cañón. Once you have reached it, the effort put into crossing the crawl passageways is rewarded by the volumes of this gallery. The problem is that if you opt for this route, you will have to return along the same route.

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