Tiered deep-sea survey: AUV wide-area mapping then crewed/ROV close inspection

Mechanism

Split the problem into two survey tiers matched to their tools:

1. Wide-area autonomous mapping. An AUV flies pre-planned lawnmower tracks a few metres above the seabed, capturing high-resolution imagery and bathymetry stitched into georeferenced photo-mosaics. This scans large areas quickly and pinpoints individual drums without a ship or humans hovering over each one.
2. Targeted close inspection. A crewed submersible or work-class ROV dives to selected high-interest drums for direct visual assessment (intact / corroding / breached), identification of coating material, on-site radiometry, and physical sampling.

Where it fits

This is the prerequisite for monitoring and disturbance-avoidance work — it produces the map and condition data everything else builds on.

Operating profile and limits

Ship- and asset-intensive (research vessel, deep-rated AUV, crewed sub/ROV), so it runs as episodic campaigns rather than continuous coverage; a single campaign inspects tens of drums out of hundreds of thousands. Autonomy and mosaicking are what make even partial coverage of a 14,500 km² zone feasible. The approach is transferable to any deep dump or wreck site with roughly known coordinates.