Level I -- A simple visual or tactile (by feel) inspection, without the aid of tools or measuring devices. It is used to gain an overview of the underwater elements of the structure.

Level II -- A detailed inspection which involves physically cleaning or removing growth from portions of the structure to assess hidden defects. This level of effort usually supplements a Level I inspection.

Level III -- A highly detailed inspection of a structure which is warranted if extensive repair or replacement is being considered. This level requires extensive cleaning, detailed measurements, and testing techniques that may be destructive or nondestructive in nature.