- 1421 m
deepest pit in Croatia

Lukina jama, the deepest pit in Croatia, has been discovered by Slovak speleologists, members of the Student University Club from Bratislava. It is situated in the northern part of Velebit massif in Lomska duliba in the Strict Nature Reserve Hajdučki and Rožanski kukovi. It has been named after Ozren Lukic, a caver killed as a Croatian soldier on Mt. Velebit. It is 1421 m deep (results of expedition "Lukina jama 2010.") and today is among 20 deepest caves in the World.


Entrance in Lukina jama
 - a crag dimensions 22,5 x 5 m.


Branislav Šmida: ..."..."What have you found?" We ask impatiently. For joy and excitement Stano cannot express himself well about depth of the pothole. Abyss! After several hundreds of meters rumbling of a stone disappear in the depth...


Results of speleological expedition "Lukina jama 2010"

Speleological expedition “Lukina jama 2010” had several goals: speleological research, especially cave diving in the siphon-lake at the bottom of the pit, new speleological map and scientific research which includes studies of the subterranean fauna, hydrogeology, physical, chemical properties and other characteristics of the pit. Cave divers and members of the Speleological section Velebit as well as CMRS, Ivica Ćukušić and Robert Erhardt, dived into the submerged passage at the bottom of the dry part of the pit for 135 m in length and 21 m in depth. During the expedition, well known Croatian cave diver and member of Speleological section of HPD Željezničar and Croatian Biospeleological Society (CBSS), Branko Jalžić, dived into the submerged passage at the bottom of the pit at 40 m in depth. This explorations have increased the overall cave depth from 1392 m to 1421 m, which makes Lukina jama the 15th deepest cave in the world.

  PUBLISHED: 27.10.2010. 16:43


Speleologica expedition  "Lomska duliba '93"

...Saturday, August 7th 9.45PM, all three of us, descended to the bottom...

From 19th July till 15th August 1993, The Speleological Committee of the Croatian Mountaineering Association (KSHPS), organised caving camp in Lomska duliba at Northern Velebit. The camp was separated in two parts. In the first, from 19th till 31st July the leader was Anđelko Novosel (SS HGD). The cave was rigged till -170 m when, due to inexperience with icy caves, descending is stopped till arrival of other explorers. From 1st till 13th August the leader was Branko Jalžić (SOŽ), while on 14th and.15th August Damir Lacković (SOV). Under their leadership exploration of the cave, still called Manual, were restarted.

When the Croatian depth record was achieved (till then it was pothole Stara škola on Biokovo, deep -576 m), on proposal of Damir Lacković pothole was renamed "Lukina jama" after caver u Ozren Lukić - Luka, killed in war at the southern Velebit a year earlier.

Feeling of exploration euphoria dominated the camp. Teams entered the cave one after another, depth increased daily. Practically every team ran out of rope.


Saturday, August 7th, 1993.
By Damir Lacković

We took ropes for further descending, but left 100 metres at the beginning of long pitch, beyond a crawl. Penetrating deeper, at 7.30 p.m. we run out of rope at the beginning of another long pitch. Siniša climbed back to pick up rope left ahead, and was back by 8.30. p.m. We have used the rope on the pitch, to conclude it is the last, at 9.45 p.m., all three of us, descended to the bottom, Damir first, than Siniša and finally Šišmiš.


Lukina jama: After a week of descending into depth, group of there: Damir Lacković (SOV), Siniša Rešetar (SOV) and Robert Dado (SOŽ) on the date August 7th, 1993 about 9.45 p.m., reached the bottom at the depth of - 1355 m.
Photo: D.Lacković

Seven days was needed for cave to be rigged till bottom including setting up of two bivaques (from 31st July till 7th August 1993), while derigging and transportation out of cave took four days (from 10th till 14th August 1993).


Ekspedicija "Lukina jama '94"

Slovakian cavers explored Trojama (Manual II) pothole in the period from 23rd till 28th July till the connection with Lukina jama at depth of -558 m, so the depth of the cave system Lukina jama - Trojama increased till -1386 m.

Trojama. Foto: B.Šmida


Cave diving at the depth of 1349 m (counting from the lower entrance) represents a kind of world record accomplished by Zoran Stipetić and Teo Barišić. Afer diving, new depth of Lukina jama from the upper entrance is -1392 m.

A big sensation on the expedition "Lukina jama '94" was a discovery, done by Ana Bakšić (Sutlović), of a new animal sort, just at the bottom of Lukina jama. This animal belongs to a new leech family. It is white and 3 cm long, lives in water at the temperature of 4°C. Moves like a caterpillar (stretching-contracting motion) and has extremities, which look like small legs. It is named Croatobranchus mestrovi. Genus received the name from the country of origin and side extremities (most probably auxiliary respiratory organs - branchia). Species name mestrovi is in honour of academician Milan Meštrov, Croatian biologist.

Lukina jama na -1200 m. Foto: A.Bakšić


Ekspedicija "Lukina jama '95"

Too early period of expedition was probable source of many difficulties. In fore - actions during June bigger quantity of ice is observed, some of earlier used bolts could not be used. After the 2nd day of expedition an avalanche of ice and snow covered rope at the depth of -140 m, where new rope had to be rigged, and at the depth of -550 m it had to be dig out. Telephone cable, used a year before, was broken too, so it needed repairing. During repairing phone cable one caver got cramps in hands due to long hours in the harness and on rope. He was pulled out the cave by windlass. This difficulties slowed down descending into the cave, so this year only two cavers reached the bottom: Damir Lacković and Robert Erhardt. During the short time at the bottom they have collected two specimen of endemic leech.


Expeditions in Lukina jama





Lokacija: Hajdučki kukovi, NP Sjeveni Velebit, Hrvatska

Depth: -1421 m

Length (horizontal): 1078 m

Explored by (1993.-1995.): The Speleological Committee of the Croatian Mountaineering Association,
SO PDS Velebit, SO HPD Željezničar, SO HPD Dubovac, SO HPD Mosor, DISKF,
SO HPD Japetić, SSHGD, SD Špiljar, SUK Bratislava



by Darko Bakšić

Entrance in Lukina jama is a crag dimensions 22,5 x 5 m. From the entrance to Whiskey chamber, at the depth of -320 m it is practically vertical. From the depth of -50 till -320 m on rocky sides could be found tick layers of snow and ice. In the first part of the cave, at the depth of -53 m and -178 m are two side passages. The upper leads into smaller chamber with icy waterfall 27 m high, while lower is meanderic, snowy and steeply goes down till a small lake at the depth of -195 m (to this point Slovaks descended in 1992). Below Whiskey chamber is a pitch 228 m high. On its bottom is a sloppy ledge 27 m long. Here, at -558 m below the surface, is connection with Trojama (Manual II). Thereafter are several minor pitches till traverse at -638 m. Starting from the traverse, a hundred metres pitch leads to a small ledge, yet another pitch of 4 m and there is entrance of a meander wide 3-5 m. Here, at the depth of -743 m the 1st bivouac is situated. Between the 1st and 2nd bivouac is a pitch of a craggy meander shape in its upper part, while it gets wider in the lower part, split by several minor ledges.

Ulazni ledeni dijelovi jame (lijevo). Whiskey dvorana na -320 m (sredina) - foto: V. Božić. Uski prolaz iz dvorane na -950 m gdje je bio 2. bivak (desno) - foto: D.Troha.

Bivouac II is at the depth of -950 m, in a chamber 85m long and 70 m wide. On the Northeast side of the chamber a narrowing connects it with the next pitch high 142 m that ends by a sloppy ledge at the depth of -1092 m. Below the ledge at -1102 m is a narrow entrance into Vjetroviti kanal (Windy passage) which is a meander 47 m long going downhill. After passing speleothemic narrowing starts a pitch of 109,5 m, followed by several shorter and finally slope till the depth of -1311 m. Here, the passage ends filled by boulders covered by clay. There is a possibility to traverse the passage a bit higher and bypass. Possibility for finding new space is not high, though. According to the ground plan this part of the cave should be connected with a small side passage, just before the bottom.

The main passage descends from the sloppy ledge at -1097 m through several minor pitches till the point of connection with the 30 m long upstream passage. Follows several minor pitches and big pitch of 95 m. Just before the bottom are two small pitches. At the bottom is a chamber 20 m long and 5 m wide with a siphon-lake in the Southeast direction. Second, smaller siphon is situated across the first. The 1st siphon is dived in length of 57 m where, after an air pocket, starts another siphon.

There are two side passages at the bottom. One is above siphon-lake at the eastern side of the chamber and it splits into two smaller passages, all together 32,5 m long. The endemic leech is discovered here. The second side passage is situated in Northwest part of the chamber 8 m above the 2nd siphon. It separates into two parts, too; one of which is extremely narrow (it has a potential for further progress, but has to be widen, by hilti), the second passage is wider and easier to pass through. Together they are 120 m long.

Bottom of Lukina jama reached so far is just 83 m above sea level, and 10,5 km far from the sea. Further flow of the subterranean streams is probably in the sea direction and submarine and coastal springs in area from Žrnovica to Jablanac.

A 3D crossection of Lukina jama-Trojama, made by D. Bakšić and Dr. V. Kušan.


Lukina jama-Trojama topo


Description of Trojama ( Manual II )

Branislav Šmida


Entrance in Trojama is a crag long 26 m and wide about 2 m. The entrance pitch is 140 m deep, with several side holes, that probably lead into parallel underground pits, still not explored.

Openings at southeastern side of the pothole are very interesting, because could be connected with the cave no. 15, which would increase the depth of the system for 3 m.

At -140 m starts icy part of the cave wide from 0,7 till 6 m. At the point where ice stops is a narrow entrance into passage called Grmač. If ice breaks, it could close the entrance. The meander is easy to pass in its middle part, but in the lower part is very narrow. After meander is a vertical named Plana stovka (Bad hundred) deep 80 m, which ends by a shallow lake. Thereafter are several smaller pits from Baldachyn till Monzunova šachta (Monsoon pitch). On the whole part from Grmač till Monzunova šachta one could not see the ceiling.

Baldachyn is a side passage with a wig where, in need, is possible to make a bivouac. Monzunova šachta, 160 m deep, connects with Lukina jama at the depth of -558 m, or at -595 m if measured from the entrance of Trojama. Stream starts here, than stronger or weaker, flows through whole lower part of the system. The depth of cave system, measured from the higher entrance is -1392 m.

Geological profile of  Lukina jama-Trojama.
D.Lacković, B.Šmida, D.Bakšić



A crossection through the Mt. Velebit incuding Lukina jama, Slovačka jama, Velebita, Meduza,
Patkovog gušt, Olimp, Lubuška jama, Ledena jama (2008.) by D.Bakšić

See also new results of the exploration of Lubuška jama and possibility of connection with Lukina jama-Trojama.


By Branko Jalžić

Extraordinary feature of the system Lukina jama is its morphology. It is characterised by vertical shape and great depth of -1392 m. For ecological point of view it is interesting for three micro climatic layers, firstly entrance icy part with the temperature of about 1 °C, secondly, middle part with the temperature up to 2 °C and bottom part with temperature till 4 °C. Important ecological factor is presence of smaller water stream starting at 550 m of depth till the bottom, where are submerged passages. Different organic remedies at rocks in this part of the cave draws a conclusion that water floods space up to several meters above the lowest, summer level. Temperature of water in the lowest part of the cave was 4 °C.

The most important discovery is that of finding endemic stygobiontic leech noticed by Ana Bakšić (Sutlović).
List of discovered animal species in Lukina jama:
Marifugia cavatica, discovered new stygobiontic leech that is the most important biological result during the expedition,  Niphargus croaticus, Aplpioniscus hercegowiniensis, Hassia stenopodium, Astagobius angustatus, one specimen of beetle from group Bathysciinae (very similar to genera Radziella known from Biokovo Mountain), Chiroptera: Cavers observed one bat in a narrow pass at -950 m depth.

List of literature about Lukina jama-Trojama

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Page created on 29. 1. 1997., last update 10.03.2015.