Oceanographers have found a dumping ground of what appears to be World War II-era weaponry 3,000 feet underwater near the coast of Los Angeles, California.

The team of researchers discovered munition boxes, smoke floats, and depth charges sitting on the ocean floor, the Los Angeles Times reported Friday.

An image shows one of the devices:

“We started to find the same objects by the dozens, if not hundreds, consistently… It actually took a few days to really understand what we were seeing on the seabed,” explained Eric Terrill, one of the survey’s leaders with the University of California San Diego’s Scripps Institution of Oceanography.

A KCAL News report shows more images of the deep-sea findings:

In its press release on Friday, the institution said the second survey was completed after researchers mapped 135 miles and found the munitions in April.

Researchers used a deep-water autonomous underwater vehicle (AUV) and another device fitted with an HD camera for the project. The U.S. Navy Supervisor of Salvage and the Office of Naval Research supported the efforts, the institution continued:

Between the 1930s and 1970s, the site was a known location for industrial dumping, including byproducts from the manufacturing of the pesticide DDT, and was initially surveyed using robotic vehicles by the same team in April 2021. The goal of the second survey was to extend maps of the seafloor using higher resolution acoustic sonar imaging techniques, to apply video imaging systems to classify objects in a previously mapped debris field, and to collect observations of deep sea ocean currents.

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The 2021 and 2023 survey findings have been received by the US Navy. According to a statement from the Navy, “these munitions are likely a result of World War II-era disposal practices. While disposal of munitions at sea at this location was approved at that time to ensure safe disposal when naval vessels returned to US ports, the Navy follows Department of Defense guidance for the appropriate disposal of munitions that aligns with state and federal rules and regulations.

Authorities are currently reviewing the findings and working to determine their subsequent actions to manage the risk to health and the environment, per the Times article.

Terrill told KPBS, “We’re still looking at the seabed through like the lens of a soda straw. So we’re surveying very small areas.”