Kovači Jama - Ponor rijeke Šujice

Useful Information

Location: Kovači, 80240 Tomislavgrad.
From Tomislavgrad M6.1/M15 southwest. At Kovači turn right to Tubolja.
(43.6760331, 17.1864980)
Open: no restrictions.
Fee: free.
Classification: KarstEstavelle KarstPonor
Light: n/a
Dimension: A=867 m.
Photography: allowed
Accessibility: no
Address: Kovači, Stipanjići, 80240 Tomislavgrad.
As far as we know this information was accurate when it was published (see years in brackets), but may have changed since then.
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Kovači or Kovači Jama is sometimes called a pothole or doline, but actually it is the sink or ponor of the Sujica river, which flows through Duvanjsko polje (Tobacco Field). Hence, it is also called the Ponor rijeke Šujice (Swallow Hole of Sujica river). The ponor is located in the hamlet Tubolja at the foot of the limestone hill which is about 200 m higher. The water vanishes into a cave which has a huge triangular portal under a vertical limestone cliff, some 20-25 m wide and 15-20 m high. Cave divers have explored the cave for some distance, which was rather difficult as the rubbish people throw into the river collects at the swallow hole.

The catchment area of the Шуица (Šujice or Šuica) is 730 km² in size. It covers the area of Kupreško polje, Šujički polje and Duvanjski polje. The springs are Veliki Stržanj and Mali Stržanj near the hamlet Stržanj. After flowing through three poljes, it sinks here again, flows west across Grabovačka planina, a bare karst with hundreds of dolines. It flows underground 5.1 km to the west in the direction of Lake Buško, reappears in Ričina spring and flows into the lake after only 50 m. This is the official end of the river.

We first classified this cave as a spring, which was based on some pages on the web about water flowing out of the cave. But actually it is a sink, where the river is swallowed by a cave. Most of the year the swallow hole swallows the river completely. During times of high water, it is too narrow to swallow, and the polje starts to become a lake. But it's also possible that there is rain on the Grabovačka planina and the karst water level rises, and water flows out of the swallow hole into the river. Such sites are even rarer than swallow holes, and they are called estavelle.