Pursue development of ROV-based and/or AUV-based acoustic metrology and inspection sensor capabilities for underwater structures such as pipelines, risers, platforms, and equipment to make detailed physical measurements of underwater structures, and/or detect and identify external corrosion, pitting, and biologic fouling, and/or detect and quantify gas or petroleum product leaks, and/or detect heat plumes resulting from cracked or degraded pipeline insulation.