Bosnia and Herzegovina lies in the Dinaric Karst region of southeast Europe. The Dinarsko gorje (Dinaric mountains) extend from northeast Italy through Slovenia, Croatia, Bosnia & Herzegovina, and Montenegro to Albania forming the largest continuous Karst landscape in Europe. The region holds huge amounts of groundwater forming some of the world’s largest Karst aquifer systems with hundreds of springs and active river caves.
The beautiful spring of the river Buna (Vrelo Bune) in the Mostar region of Bosnia & Herzegovina for example is one of the largest springs in Europe and strongest in Europe in terms of water discharge.
Whilst research of the regions‘ Karst landscape has been conducted since centuries, cave diving expeditions have been started in the eighties by the local divers and more notably in the late nineties by French cave divers of the FFESSM (C. Touloumdjian et al).
In 2004 divers Renato Raseta and Hugh Reid formed the Karst Odyssey project in order to better explore and document the caves of Bosnia and Herzegovina. During annual expeditions over the last 10 years the international team has successfully explored and documented many caves in various regions around the country. Even to this day only very few divers have visited the caves of Bosnia and Herzegovina and the country is not yet widely known as a prime cave diving destination.
Exploration projects in Bosnia require almost complete self-sufficiency and an enormous logistical effort, since the country has very limited diving infrastructure and support. Most caves are protected and located on state property and obtaining diving permits can often be a lengthy and somewhat challenging process.
Since the beginning Karst Odyssey has had a great relationship with local divers from the BUK diving club in Banja Luka and over the years many club members have taken cave training and joined the project or simply provided invaluable logistical and surface support. The team has set up a full exploration base at the club in order to ease the logistics with most of the diving equipment permanently stored in Bosnia and a full mobile mixed gas filling infrastructure established.
Previously the Karst Odyssey team has focussed on the exploration of various caves around the towns of Sanski Most, Drvar and Mostar (http://www.karstodyssey.com).
In recent years the team had shifted it’s attention to the caves in the very south of the country. During two highly successful projects in 2013 and 2014 a large deep cave in the countries southernmost municipality of Trebinje was explored and several hundred metres of new cave found and surveyed. The cave itself is very characteristic of a lot of caves in the area in that it quickly reaches depths below 80m (260 feet) before it eventually becomes shallower with well-defined passage. Many of the submerged river caves in Bosnia are known to eventually surface along its path through the mountain ranges requiring dry caving techniques after a long decompression dive.
The cold water temperatures of 8 degC (46 Fahrenheit) combined with the depth make long exploration dives logistically difficult and Halcyon RB80 rebreathers together with additional heating systems and dry habitat decompression become a necessity in order to conduct safe exploration and to shelter from the cold.
During the project several other caves in the area have been documented some of which can only be dived in the winter and spring months when water levels are high enough often requiring sidemount configuration to pass a number of restrictive points in otherwise large passage.
In 2015 the team decided to shift its focus to the northern parts of the country again and to re-visit a number of caves that have been successfully explored in recent years (Quest 2009, Vol10 No.3). The closer proximity to the projects base in Banja Luka made logistical support slightly easier and during a series of long and deep dives the team managed to fine-tune procedures for future exploration. In particular safe and efficient habitat installation and deep as well as shallow support procedures for the RB80 divers were successfully practised in order to allow exploration of some of the regions deep caves over the next years.
In 2009 the team has explored another cave that was revisited during this years project. The cave is located 4km from the nearest village in a very remote and steep valley along a breathtakingly beautiful mountain range. All diving equipment has to be hand carried down a steep path and along several hundred metres of moist riverbed where a beautiful resurgence pool is surrounded by steep cliffs.
The cave itself is shallow with a depth of around 25m and a lot of high and narrow rift like passages often changing shape and direction. Previous exploration ended in a narrow chamber with a steep waterfall requiring vertical dry caving techniques to safely explore further. The waterfall chamber lies right beyond a severe restriction that makes it difficult for a large dive team with additional dry caving equipment to operate in this section. Since it’s discovery the team was intrigued by what lies beyond the waterfall and in 2015 a reconnaissance dive was finally conducted to establish the best method for future exploration. On a strike of luck a massive bypass to the restriction and waterfall was discovered together with ongoing cave passage and Karst Odyssey is currently planning a large-scale exploration project for next year.
Any GUE divers interested to participate and support Karst Odyssey’s cave
Exploration project in Bosnia and Herzegovina can contact the team via Facebook or under www.karstodyssey.com.
2015 Team members
Branislav Radevic (BIH)
David Dusek (CZE)
Dusan Milosevic (BIH)
Emir Memic (HRV)
Osama Gobara (AUT)
Renato Raseta (UK)
Photographs: David Dusek
This article was printed in GUE’s Quest magazine https://www.gue.com/quest/17/1