Sinkholes have been appearing across central Croatia after December's deadly earthquake.
A number of craters have been found in a sparsely-inhabited region, around 40 kilometres southwest of the capital, Zagreb.
Scientists have been rushing to Mecencani and other villages to observe and study the round holes.
"These are so-called dropout sinkholes," said geologist Josip Terzic of the Croatian Geological Survey.
"They appeared because of the specific geological composition of this area, as the soil rests on limestone rocks heavily saturated with groundwater."
Two months ago, seven people were killed in Croatia after a 6.4 magnitude earthquake caused severe damage to the town of Petrinja. An estimated 100 sinkholes have been spotted in the region since.
Many of these have appeared next to houses and on farmland, prompting local authorities to advise caution.
While the appearance of sinkholes is not unusual following strong seismic activity, residents have been surprised by the number that has been found and the speed at which they emerged.
Geologists have said that the earthquake accelerated the process of sinkhole formation that would normally have taken years, if not decades.
Terzic said scientists are planning various exploration methods to determine the underwater morphology of the sinkholes and other characteristics.
As the Balkans region sits on a faultline, earthquakes are common in Croatia but they are usually not severe.