People on boats off Jersey have been urged to use safety equipment properly by the RNLI.
Two lifeboats were launched after a flare was released, but no-one appeared to be in distress, the charity said.
The incident happened on Saturday evening at about 21:00 BST when both of the St Helier's lifeboats were launched.
After an extensive search by a volunteer crew nothing was found, the RNLI said.
A charity spokesperson said: "The red flare is a distress signal for trouble at sea at night.
"The RNLI urges people to use safety equipment appropriately."
