'EY' was the British naval undertaking to locate and destroy suspected moored mines off the Seyðisfjörður in eastern Iceland (8 October 1942 onward).
The 15th Minesweeping Flotilla (Ardrossan, Beaumaris, Dunbar, Fraserburgh, Llandudno, Lyme Regis and Worthing) departed Loch Alsh and Scapa Flow for the Seyðisfjörður, where it began its sweeping operations on 10 October. Some days later, after several mines had been swept, Dunbar, Lyme Regis and Worthing departed for British waters, but later returned to the Seyðisfjörður to continue sweeping. On 15/16 October the light anti-aircraft cruiser Argonaut and the destroyers Intrepid and Obdurate, involved in 'EZ', were swept into and out of the Seyðisfjörður, and from this time onward German aircraft kept an aerial eye on the British undertaking, apparently with some success in establishing the channel the British vessels had swept.
On 18 October the squadron’s commander reported that he suspected that the squadron’s dan buoys were being sabotaged and instituted night patrols to guard them. The British could provide no fighter protection for the operation as a result of the distance from the nearest airfield at Reykjavik. On 22 October the flotilla was reinforced by Bootle, which arrived from Scapa Flow with stores and minesweeping equipment. Dunbar had already left the flotilla for Cardiff and boiler cleaning, and Beaumaris was compelled to spend two days at Akureyri, to which she was escorted by Llandudno, for her propeller to be cleared by divers. The two vessels rejoined the Flotilla on 22 October, at which time it was estimated that the operation would continue until the end of the month.