Diver Finds Structure on Ocean Floor — Then Finds Out Why It’s There

A vertical drop

The shaft walls were smooth as if they had been intentionally bored through the structure. Eli descended slowly, carefully watching the readout on his depth gauge. Twenty meters down, the shaft suddenly opened wide. The darkness was still there, but this time, much less cramped. Eli steadied himself mid-water, spinning slowly as his flashlight cut through the gloom to reveal walls that kept going—and going.