The powerful north Atlantic.

[Graham Easterling]

It's not commonly known, but the highest average swell size in any month, is not in the Southern Ocean, but in the north Atlantic, just SW of Ireland, in January. This is because the prevailing W-SW winds have a very long great circle route byt the time they get to Ireland. 

This is Sennen during a particularly big swell. - 8-10m significant wave height. (Biggest waves 50% bigger.)

Doesn't the breakwater look insignficant. To give some idea of scale, see below. Note the height of the men against the lifeboat house, which looks so small and vulnerable in the first photo.

Graham

Penzance - 2 lovely days, reached 18.4C today. A stroll around St Ives yesterday