The northeastern side of Halkidiki, in northern Greece, has a long history of mining activity. Currently three exploitation areas exist namely Olympiada area with an estimated mined production of 11.5 million tons of ore, Skouries area of the world-class porphyritic deposit with an estimated mined production of 146.2 million tons of ore and Stratoni area with total reserves of 1 million tons of ore. The overall development of Kassandra mines is considered as a mega-project with numerous challenging civil works (surface and underground) and earthworks. In underground infrastructure, the most notable works completed or currently under construction include Kokkinolakkas stream diversion tunnel, 1,140m long, Olympias main access tunnel, ~9km long, Skouries spiral decline, ~5.5km long and Skouries access shaft, ~700m deep.