Vertical shaft mines hold the record for being the deepest mines in the world. Most are located in South Africa due to its abundance of diamond and gold deposits. As of 2003 the deepest mine is the East Rand mine at 3585 meters, but as technology improves and the search for natural resources continues many mines are constantly being deepened. In the next few years, the Western Deep mine will reach 5 km.
Many problems arise when digging so deep into the Earth. The most obvious is the heat. For example, at 5 km the temperature reaches 70 degrees Celsius and therefore massive cooling equipment is needed to allow workers to survive at such depths. Another problem is the weight of the rock. For example, at 3.5 km the pressure of rocks above you is 9,500 tones per meter squared, or about 920 times normal atmospheric pressure. When rock is removed through mining this pressure triples in the surrounding rock. This effect coupled with the cooling of the rock causes a phenomenon known as rock bursts, which accounts for many of the 250 deaths in South African mines every year.