Three people were rescued after getting into difficulty in the water at Benllech beach.
The RNLI's all-weather lifeboat from Moelfre and the Coastguard helicopter from Caernarfon were called out on Sunday afternoon amid rough seas and a strong offshore wind.
One person was found further out to sea by the helicopter while the ALB launched its daughter boat and rescued the other casualties, who were taken back to shore.
Mike Hughes-Roberts, coxswain at RNLI Moelfre, said: "The individuals were trying to swim out to a boat that had slipped its anchor in rough seas with a strong offshore wind."
"Conditions can change so quickly, and it is vitally important to stay vigilant when dealing with the sea. It can be so dangerous and unforgiving if not shown the respect it deserves."
"Always check the weather conditions and consider your capabilities. If in doubt – it is better to stay out of the water. Have a means of contact such as a mobile phone, if you get into trouble or see anyone else in difficulty, call 999 or 112 and ask for the Coastguard."
"If you do get into trouble in the water, Float to Live. Tilt your head back with your ears submerged, try to relax and control your breathing. Use your hands to help you stay afloat, don’t worry if your legs sink – as we all float differently."
"Once you’ve gained control of your breathing, call for help or swim to safety if you can."


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