Fig. 8: Before one can go ice diving, one has to cut a hole in the ice. A triangular shape is the best for getting in and out of the water. Due to the mild winter the ice was only 20-30 centimeters thick. Only half of it was black ice. DiveZone ice diving event, Lake Klöntal. Nikon D3; Δt=1/320 s; f=48 mm; f/9.0; ISO 200; 1 March 2014 11:17:05
