Marine mining technology only became commercially viable in the early 1990s. Marine diamond mining employs both "vertical" and "horizontal" techniques to extract diamonds from offshore deposits. Vertical marine mining uses a 6 to 7 meter diameter drill head to cut into the seabed and suck up the diamond bearing material from the sea bed. Horizontal mining employs the use of Seabed Crawlers (remotely controlled, CAT-tracked underwater mining vehicles) that move across the sea floor pumping gravel up to an offshore vessel.
Alluvial Mining
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Alluvial or Placer Diamond Mining, also known as "sand bank mining" is used for extracting diamonds and minerals from alluvial secondary deposits. Sand Bank Mining is a form of open-pit or open-cast mining used to extract minerals from the surface of the earth without the use of tunneling. Excavation is accomplished using water pressure (hydraulic mining), mechanized surface excavating equipment, or digging by hand (artisanal mining).
Kimberlite Pipe Mining
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Diamonds form at a depth of upto 200km beneath the earth's surface. After their formation, diamonds are carried to the surface of the earth by volcanic activity. A mixture of magma (molten rock), minerals, rock fragments, and occasionally diamonds form pipes shaped like champagne flute glasses as they approach the earth's surface. These pipes are called Kimberlites.
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