A personal beacon sparked a false callout for emergency services in the Aberdaron area.
The RNLI at Porthdinllaen sent out its lifeboat crew following reports of a PLB being activated at around 3pm last Thursday afternoon.
The coastguard rescue helicopter from nearby Caernarfon Airport was also tasked to the suspected location.
But following an investigation by Holyhead coastguards, the lifeboat crew were told near Porth Colmon they were certain there were no lives in danger nor any person unaccounted for.
The incident was deemed as a false activation.
A personal locator beacon is a small, handheld personal device that is usually carried by fishermen and sailors - they can be used on land or at sea and are best attached to a lifejacket or a similar device to easily alert rescue services in case of an emergency.
Kenneth Fitzpatrick, lifeboat operations manager at RNLI Porthdinllaen said: "We advise all fishermen, especially lone workers or sailors, to be equipped with the Personal Location Beacon as the device can prove to be invaluable in locating the casualty should they find themselves in need of assistance."
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