This is a complex, high technology activity that has its roots in the seismic characteristics of the Earth. Seismology, as practiced commercially in the search for hydrocarbons, is a large and in places very complex subject. The field activity is conducted by advanced survey vessels with typical size of approximately 300ft (5-6000 gross tons), equipped with an energy source (compressed air) to create sound waves and listening cables to register the “echoes” or returned sound waves from the subsurface of the sea bottom. The typical crew onboard the vessel consist of approximately 28 people, of which 12 people are the maritime crew and the rest represents the experts in various disciplines needed to acquire seismic data. The result of the data acquisition is partly analyzed onboard and stored on high capacitive data storage media (Mass Storage System) for further processing and analysis after being received in a data processing centre. The amount of data stored is enormous, for each survey line with approximate length of 23 kilometers typically 7-8 data cartridges are recorded and each cartridge is capable of holding 1 Gigabytes of data. In seismic surveying, energy is generated onboard a survey vessel to produce waves and send them into the earth. This energy wave doesn’t just vanish into the earth’s crust. Some of it is reflected back to the surface and we detect the returning waves with sensitive measuring devices that accurately record the strength of the wave and the time it has taken to travel into the earth’s crust and back to the sur­face. We can then take these recordings and after various adjustments, done mostly by computers, we can make them into visual pictures that give us a good idea of what the subsurface of the earth is like beneath the seismic survey area. So in summary, we cannot see directly what the rock layers are doing beneath the surface but we can use seismic surveying to get the picture indirectly.