The Dalnegorsk Incident, often called the "Roswell of the Soviet Union," occurred on January 29, 1986, at 7:55 pm in Dalnegorsk, Russia. Eyewitnesses saw a reddish or orange-reddish spherical object, about three meters (or 10 feet) in diameter, flying noiselessly and parallel to the ground. Its color was described as similar to burning or burnished stainless steel. One witness noted it ascended and descended, its glow intensifying each time it rose. It "jerked" and fell down like a rock before crashing into Izvestkovaya Mountain, also known as Height or Hill 611. A powerful impact was heard. There was an explosion and a fire that burned for varying durations, reported from a few minutes to about an hour or more. One report stated the object made six attempts to take off while aflame before slowly rising and flying away an hour later.

Days after the event, a team led by scientist/ufologist Valeri Dvuzhilni investigated the crash site. They found a high-temperature exposure site about 2x2 meters (6.5' x 6.5'). Rocks were covered in a black film, the ground was black ash, and a burnt tree stump turned to porous coals. The burned area was sharply defined.

Materials collected included melted drops with a metallic tint, solidified droplets, black vitreous particles, and unusual loose scaly particles called "tiny nets" or "mesh".

Analyses in Soviet laboratories revealed unusual properties. Smaller metallic drops were a lead alloy with up to 17 elements. Larger ones were extremely hard compounds requiring a diamond saw to cut. The metal alloy was amorphous. Vacuum melting caused elements like gold, silver, and nickel to disappear, while molybdenum and beryllium sulfide appeared. The mesh was amorphous carbon containing numerous elements, including rare earth atoms, zinc, silver, and gold. It contained very thin (17 micrometers) quartz threads twisted into bundles, interwoven with even thinner gold wires. Experts found the technology and structure difficult to understand or reproduce with technology at the time. Silicic shale rocks at the site were magnetized. The isotopic composition of lead suggested a terrestrial origin from the northern Baikal region.

The crash site was described as an anomalous zone with adverse effects on people, including blood changes, high blood pressure, quickened pulse, inexplicable fear, sensor failure, and loss of coordination. It also affected photographic materials. Electromagnetic fields reportedly caused interference and corrupted computer files during UFO activity.

Following the crash, high UFO activity was reported in Dalnegorsk. In November 1987, numerous objects were seen, some flying over or hovering near Height 611 and illuminating it, witnessed by over 100 people, including military and police.

While some theories proposed natural phenomena or military technology, the unusual materials led some scientists, including Dvuzhilni and Doctor of Chemical Sciences V. Vysotsky, to conclude the object was likely an artificial space probe of non-terrestrial origin. The earthly origin of the object has not been convincingly proven. The incident is considered by some to be the "best documented crash" due to the recovered fragments.