Nowadays most marine/offshore construction activities require the study of sub seabed and its vicinity in order to analyze and determine the best and safest position.
For example, before placing a jack-up rig in the proposed position, the survey team must have the soil to determine the subsurface condition and materials, the physical and chemical properties of those materials, etc. Beside the placement of offshore platforms, submarine pipe-lay activities usually also require soil information of the area. This is what Geotechnical Survey is all about. Using principles of soil and rock mechanics ,the survey will help determine:

1.    Standard Penetration Test (SPT)
2.    Soil boring
3.    Cone Penetration Test (CPT)
4.    etc