The Weber Deep sits in the eastern Banda Sea, surrounded by the islands of the Banda Arc: Watubela, Timor, Buru, Seram, Ambon, and Kur. To its west lies the Banda Volcanic Arc, a chain of active volcanoes including Manuk, the nearest volcanic island to the deep itself. What makes the Weber Deep unusual is its origin. Most oceanic depths of this magnitude form at subduction zones, where one plate slides beneath another. The Weber Deep is instead a forearc basin, created when a section of crust approximately 120 kilometers long broke away along a low-angle crack called the Banda Detachment. The rip exposed some 60,000 square kilometers of fault plane, an area roughly twice the size of Belgium. In places along the deep, the ocean floor has no oceanic crust at all, only the exposed mantle rock beneath. The deep stretches about 450 kilometers from north to south, and its floor dates to between 3 million and 500,000 years old, young by geological standards.

The fault beneath the Weber Deep remains active. Its most catastrophic recorded event occurred in 1629, when a megathrust earthquake estimated at up to magnitude 8.8 generated a 15-meter tsunami. The aftershocks continued for nine years. That single seismic sequence rivals the most powerful earthquakes in recorded history, though it occurred centuries before modern instrumentation could capture its details. The Banda Sea has continued to produce significant earthquakes in the centuries since, including notable events in 1852 and 1938. The geology that created the Weber Deep is not finished. The eastward expansion of the Banda Sea continues to widen the basin, and the fault system that produced the 1629 cataclysm shows no signs of quieting. Flying over the Banda Sea, the surface gives no indication of the forces at work beneath it. The water is calm, blue, and indistinguishable from any other stretch of tropical ocean.

The deep takes its name from Max Carl Wilhelm Weber, a Dutch-German zoologist who spent his career studying the marine life of the Indonesian archipelago. Weber was a professor at the University of Utrecht and later the University of Amsterdam, and his first voyage to the Banda Sea came in 1881. In 1898, he led the Siboga expedition, one of the great marine biological voyages of the nineteenth century. The expedition departed from Surabaya on March 7, 1899 aboard the Siboga, a 53.7-meter gunboat of the Dutch East Indies navy, and spent nearly a year surveying Indonesian waters. Weber's wife, Anna Weber-van Bosse, sailed with him as a scientist in her own right, one of the first women to participate in a major oceanographic expedition. The Siboga expedition cataloged thousands of species, nearly half of them new to science, and conducted the depth soundings that would give Weber's name to the abyss.

Weber and the Siboga identified the deep, but it was not precisely measured until 1929, when the Dutch survey vessel HMS Willebrord Snellius carried echo-sounding equipment through the Banda Sea on an oceanographic expedition that lasted from March 1929 to November 1930. The zoologist Hilbrand Boschma was among the expedition's scientists. Two decades later, the Danish Galathea Deep Sea Expedition of 1950-1952 returned for a more thorough survey. The Galathea's researchers sent sampling equipment to the bottom and brought back evidence of life at extreme depth: deep-sea sea cucumbers and aerobic bacteria surviving under crushing pressure and in total darkness. The Weber Deep ranks as the 16th deepest point in the world's oceans and seas, but it holds a distinction no trench can claim. It is not a wound from collision but from separation, a place where the planet pulled itself apart and the sea rushed in to fill the gap.