The Harry Kim wormhole was the name that Tom Paris proposed petitioning the Federation Astronomical Committee to officially designate the wormhole discovered by Harry Kim in the Delta Quadrant in 2371.
Although exhibiting the usual properties of a wormhole, including verteron emanations and tunneling secondary particles, it was discovered that the wormhole was in an advanced state of decay thought had been occurring for centuries, having collapsed to a width of approximately 30 centimeters. The Voyager crew sent a microprobe into the wormhole, where it encountered extremely dense microscopic gravitational eddies and extremely constricted spatial dimensions.
While traveling through the wormhole, the microprobe became mired in a gravitational eddy, becoming lodged in the wormhole. The Voyager crew was able to use the microprobe as a communications relay, contacting the Romulan science vessel Talvath in the Alpha Quadrant. The vessel's captain, Telek R'Mor, was able to beam to Voyager using the probe as a relay. Scanning R'Mor, Lieutenant Tuvok found that he was exhibiting clear signs of temporal displacement, and discovered that the wormhole was a rift not only in space, but in time as well, connecting to twenty years in the past.
Realizing that they could not beam the crew through the wormhole due to the effects it would have on the timeline, they were forced to abandon the plan, and transported R'Mor back to his ship. (VOY: "Eye of the Needle")