Visibility varied from zero to three feet on the bottom, though it was significantly better in the mid-water column.
Theory is nice, but field work is different.
Even with the high tech tools, search patterns on the bottom consumed most of the water time for the teams. Object typically would be encountered 10-20 meters away from the drop point. Finding anything in the ocean can be difficult . Large scale changes really date back to the era of pineapple plantations beginning in the early 20th century, when large tracts of land surrounding the Bay were cleared and cultivated, vastly increasing the soil erosion rates from the island. Pavement, sewers, and culverts all increase runoff and siltation in the Bay.