See Code of Federal Regulations 23 CFR 650.305. There are three (3) levels of diving inspection, Levels I, II, and III, with increasing complexity from low to high:
a. Level I – Generally used to detect major damage, confirm drawings, or gain more information to plan a more in-depth inspection. This level is essentially a “swim-by” overview of 100% of underwater elements, which does not involve any structural elements cleaning.
b. Level II – Generally used to detect and identify damaged/deteriorated areas that may be hidden by biofouling or surface deterioration. The level requires detailed inspection of 10% of underwater elements and requires some cleaning. Elements are cleaned in 1-foot-high bands at near low waterline, at the mudline, and midway between.
c. Level III – Typically completed to investigate a deficiency detected under Level I or Level II inspections. This level often requires the use of non-destructive testing techniques and may also require the use of partially destructive techniques such as sample coring, material sampling or in-situ surface hardness testing.