You can still see blue tarps when driving via some of Puerto Rico’s interior. Not all of them, nor as many as in 2018, but enough to indicate what remains unfinished. One of the most devastating storms to ever hit the island, Hurricane Maria made landfall in September 2017. Since then, the recovery has been genuine but uneven, with a patchwork of rebuilt schools, neighborhoods, and still-vulnerable infrastructure that has taken longer than most people anticipated due to the island’s financial situation and a complex federal relationship. Although not always so, the power grid is now more resilient than it was. Some communities still use borrowed time for their water systems.
Scientific survey ships have been lowering sensors into the Puerto Rico Trench, the deepest point in the Atlantic Ocean at about 8,376 meters below the surface, a few hundred kilometers north, at depths that the island’s inhabitants seldom ever consider. Over the past few years, research teams affiliated with the USGS and university partners have been mapping the trench system with ever-higher resolution using multibeam sonar and remotely operated vehicles to record fault line geometry, submarine landslide scars, and the topography of a seafloor situated at the meeting point of the Caribbean and North American tectonic plates. Understanding where the next significant underwater landslide might occur, how a massive fault rupture in the trench might cause a tsunami, and what the seismic risk profile looks like for the island lying above it are all part of the work’s geological hazard assessment framework.
This surveying has a more subdued mineral component. Governments and the extractive industries that monitor vital mineral supply chains are now strategically interested in the elemental composition and material distribution data obtained from deep-sea sediment cores and chemical analysis of bottom samples. Similar to other deep Atlantic and Pacific systems, the Puerto Rico Trench region has accumulations of elements that have drawn increased attention as demand for materials that terrestrial mining finds difficult to supply in sufficient quantities is driven by battery manufacturing, semiconductor production, and energy infrastructure.
The subject of whether commercially relevant amounts are present on the seafloor in Puerto Rico is still up for debate in science. No one has yet raised the political question of whether those resources, if they exist, would help the island or just be administered from Washington under the same federal frameworks that control the rest of Puerto Rico’s territorial connection with the mainland.
The practical reality of Puerto Rico’s connection with federal resource governance from the inside out clashes with that political aspect. The Congress that establishes those policies does not have any voting representation from the island. A territorial framework that was created in 1917 and was based on different presumptions than those pertinent to deep-sea mineral policy in 2026 filters its involvement into federal environmental and resource management choices about its surrounding waters. The disparity between how actively the seafloor is being investigated and how little of that discussion takes place in San Juan as opposed to Washington gives the impression that the island is being scanned without real consultation.
The seafloor research’s marine ecosystem component provides another layer that is more closely related to the resources that Puerto Rican populations rely on. Fish populations that sustain both commercial and subsistence fishing are supported by deep-water coral systems in the upper slopes of the trench. Ongoing surveys are monitoring how the benthic ecology is recovering—or, in some cases, not recovering—from the substantial sediment disturbance that Maria’s effects on coastal watersheds caused to those coral colonies. In ways that the baseline surveys conducted prior to the storm enable researchers to measure with some degree of accuracy, the temperature changes impacting Caribbean deep water are making that recovery more difficult.
