The competition starts in the northern part of the Pearl Gulf in Primorsko, on the beach near the Lion Heart base camp. It includes two laps of 1500 m each. The trace marked by buoys is parallel to the shore at distance of 100 m from it. For the safety of the swimmers teams of Bulgarian Red Cross Life Guards will watch over with kayaks and motor boats. The depth is about 4 m and goes above the ruins of the sunken ancient Thracian city of Ranuli, the main entrance to the former lands of the Asti tribe.
After finishing the swimming leg the athletes go through base camp and continue with the cycling leg.
The start and the finish of this leg crosses a 20 m wide beachline with fine, golden sand. The swimming trace leads the competitors 100 m into the sea following a floating rope, then it turns to the right (south) and makes two laps clockwise following the floats. They are always on the right side of the athletes. After the second lap the competitors come out from the sea on the same side of the rope as they went in (the floating rope should be on their left side), cross the beach and enter into the “ultra” corridor to the transit area OR the “relay-race” corridor.
The depth is between 4 and 6 meters and even a small wave could hinder the floats from view. The water in the Perla gulf is clean, clear and algae as well as jelly-fish are almost absent. The gulf bottom covers a sunken town, which makes the bedrock extremely variable. This is a precondition for streams, but thanks to the larger depth they are avoid. There are shallow and deep zones in the first 50 metres of the sea entry.