The Puerto Rico Trench & the Virgin Islands Trough - What Lurks Beneath?

Jamie Leonard

Off the Coast of St. Croix - The Puerto Rico Trench is the deepest point in the Atlantic Ocean and one of the most geologically complex regions on the planet. It stretches nearly 800 miles - roughly the distance from Boston to Chicago - running east-west across the northern edge of the Caribbean. This vast undersea gorge passes north of Puerto Rico, continuing past the U.S. Virgin Islands, and arcs out into the open Atlantic. At its deepest known point, called the Milwaukee Deep (aka the Milwaukee Depth), the seafloor plunges to approximately 27,500 feet, deeper than Mount Everest is tall.

Despite its size, the trench is named for Puerto Rico because its deepest and most extreme section lies directly north of that island. The name reflects the location of maximum depth, not the full span of the trench itself. In reality, this system is shared by the entire northern Caribbean region, including St. Croix.

The trench exists where the North American Plate is being pulled beneath the Caribbean Plate, generating powerful tectonic tension, crustal thinning, and deep sea faulting. This ongoing deformation has created one of the strongest negative gravity anomalies on Earth. Gravity here is about 0.04% weaker than average - a difference too small to change a person’s weight in any meaningful way (a 200-pound person would weigh about 199.9 pounds). But the significance is not human weight - it is what the anomaly reveals about the environment. 

The thinning crust and shifting density layers create unusual underwater acoustics, magnetic field variations, and zones where sonar returns can fade or scatter. In simple terms, the trench functions as a natural concealment zone, a place where objects beneath the surface could move without being easily detected.

This may help explain why the region is also a well-documented UAP (Unidentified Aerial Phenomenon - aka UFO) hotspot, particularly for transmedium objects capable of moving between air and sea. The 2013 Aguadilla UAP incident, captured in the U.S. Customs and Border Protection infrared camera, shows an object over Puerto Rico’s coastline before entering the ocean without any splash and then continuing underwater at great speed - exhibiting no visible propulsion or conventional flight surfaces. 

Commercial airline pilots flying San Juan, Puerto Rico, routes between 2020 and 2023 have reported metallic spheres pacing aircraft before descending toward the trench and vanishing from radar coverage. Meanwhile, U.S. Navy sonar operators have privately acknowledged “dead zones” in the basin where tracking simply fails. 

For St. Croix, the connection is direct and visible from shore. Just north of the island, the seafloor drops sharply into the Virgin Islands Trough, a deep-ocean basin reaching 16,000 - 19,000 feet that feeds into the trench system. Local divers know this drop as the Cane Bay Wall - a place where, after a short swim, the sea floor falls away into a vast, dark expanse. Divers describe a sense of floating over a void that feels unlike any other dive site in the Caribbean. 

Local fishermen, especially along the north and west coasts, have long described glowing white or amber orbs rising from or descending into these deep waters - stories that predate the modern internet by decades. Many describe silent motion, no navigation lights, and behavior that suggests the craft has a sense of awareness - altering its course or dimming its lights when approached.

Scientists do not claim these objects are extraterrestrial. But they do agree on the following points:

• The trench near St. Croix is deep

• It is Unmapped

• Acoustically complex

• Difficult to monitor

• And ideally suited for hiding activity

So for St. Croix, the puzzle is not whether the trench is remarkable, which it is, the real question seems to be:

What, if anything, is moving in the darkness below the Wall?