Markings on Ice
Fig. 3: A circle around the hole with spokes are helping for orientation under water in case a diver looses the rope. DiveZone ece diving event, Lake Klöntal. — EXIF: Nikon D3; Δt=1/400 s; f=28 mm; f/10.0; ISO 200; 2014-03-01 11:09:57