A search of Sulby Reservoir was carried out after several members of the public reported seeing a red flare in the sky.
The operation was completed by 10.45 last night, by which time authorities were satisfied the area had been effectively scoured with nothing being found.
The reports of a flare were made just after 6.30pm, but its source remains unknown.
(Picture: Sulby Reservoir, from manxscenes.com).