Though the exact depth of the cave is unknown, some speculate that it could be the deepest underwater cave in the world. In 2007, the cave ranked 77th, after being explored by diver Mark Vandermeulen, on a list of the deepest underwater caves. Vandermeulen was also part of this year's diving team. Vrelo ranks 14th on the list of the deepest caves explored by humans, and some speculate it might be underestimated.
Diving approximately 212 metres, an international team of divers and speleologists explored the subterrain recently. The team of 13, made up of Italian, Belgian and Macedonian divers, believe that the cave is actually deeper than reported, but had to call off their ten-day mission due to muddied water caused by heavy rain.
Longitudinal cross-section of Vrelo
How to get there: only by boat. Boats (approximately for 10 people) start in the front of the Hotel-restaurant Canyon Matka. The price for 1 person is 400 denars (about 7 euros), which covers transportation to the cave and the entrance, with short info by the boatman. It takes about 1.5 hour for this trip.
The cache is a small white plastic container. Please, be aware of snakes, especially in summer! The cache is hidden near the cave entrance. To find this cache in discretion, when the visitors go back to the boat, pretend you forgot something there and quickly find and log 
!!! Bond, James Bond, would accomplish this task within few seconds!
The GPS signal along the canyon is usually very poor! Please, consider the published coordinates only as approximative! Use the photo spoiler to locate the cache, please.
You can reach Lake Matka by bus, by car or a bike. The city bus (number 60) runs from central Skopje via Saray to the Matka dam (check the schedule on the JSP website, http://www.jsp.com.mk/VozenRed.aspx). By car or bike: go west from Skopje and turn left across a new bridge toward the municipality of Saray. Continue toward the village GLUMOVO. Behind the village Glumovo the road splits in two. Turn downhill left and continue through the village Dolna Matka about 2 km. During weekends and festivals the place is crowded by people and cars, so there can problem to park the car. However, if you come early in the morning it will be no problem to park.
Sources: Internet; Photos: Internet, Original (by Galejnik)