Red Lake ( hr, Crveno jezero) is a

sinkhole A sinkhole is a depression or hole in the ground caused by some form of collapse of the surface layer. The term is sometimes used to refer to doline, enclosed depressions that are locally also known as ''vrtače'' and shakeholes, and to openi ...

containing a karst lake near the city of Imotski,

Croatia , image_flag = Flag of Croatia.svg , image_coat = Coat of arms of Croatia.svg , anthem = "Lijepa naša domovino"("Our Beautiful Homeland") , image_map = , map_caption = , capit ...

. It is known for its numerous

cave A cave or cavern is a natural void in the ground, specifically a space large enough for a human to enter. Caves often form by the weathering of rock and often extend deep underground. The word ''cave'' can refer to smaller openings such as sea ...

s and remarkably high cliffs, reaching over 241 metres above normal water level and continuing below the water level. The total explored depth of this sinkhole is approximately 530 metres with a volume of roughly 25–30 million cubic metres, thus it is the third largest sinkhole in the world. Water drains out of the basin through underground waterways that descend below the level of the lake floor. The deepest known point of the lake is 4 metres below sea level. The sinkhole is named after the reddish-brown colour of the surrounding cliffs, coloured by iron oxides. Like the nearby Blue Lake, it is presumed that the lake emerged when the ceiling of a large cave hall collapsed. The lake is inhabited with endemic and endangered spotted minnow ('' Delminichthys adspersus'') and Imotski

spined loach The spined loach (''Cobitis taenia'') is a common freshwater fish in Europe. It is sometimes known as spotted weather loach, not to be confused with the "typical" weather loaches of the genus ''Misgurnus''. This is the type species of the spiny ...

('' Cobitis illyrica''). In the dry period of the year, this fish can be occasionally seen in surrounding springs, rivers and lakes, suggesting that there is an underground connection between Red Lake and other water bodies. At the 13th International Congress of Speleology in 2001, new findings were revealed. An inflow cave-shaped canal that measured approximately 30 × 30 metres was discovered in the eastern part of the lake at a depth of 175 metres.

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*{{Commons category-inline, Red Lake, Croatia
Stamp by Croatian post
Lakes of Croatia Sinkholes of Europe Karst formations of Croatia Landforms of Split-Dalmatia County Caves of Croatia Imotski