1982 Harpoon missile misfire incident

On 6 September 1982, a frigate, the HDMS Peder Skram, accidentally fired a Harpoon missile during maneuvers in the Kattegat. The missile traveled 34 kilometers at low level, severing several power lines before striking some trees after which it exploded. The fireball and subsequent shock wave destroyed four unoccupied summer cottages, while damaging a further 130 buildings in the immediate vicinity. No human injury was reported.

Cause
A navy investigation into the matter initially concluded that a technical malfunction was the cause of the launch as it happened without the launch key being activated. The missile system had undergone maintenance and was in the process of being checked by an expert from the navy materiel command. He was charged for negligence and was eventually convicted. Later most charges were dropped by a second investigation. The manufacturer of the missile later paid the Danish government a compensation, which covered all the damages made by the missile.

USS Coontz incident
On 14 July 1981, the USS Coontz (DDG-40) off St. Croix experienced a similar incident also involving a Harpoon missile, which impacted in the ocean.