Furnas, in its sheltered corner, can often be the only place working in a big N or NW swell. There's a right hander that breaks out off the headland, but only wakes at a serious size, when it can produce long, rolling, double overhead walls. A powerful wave breaking in deep water. In smaller conditions there are a few peaks along the beach - but not a high quality spot.
Source: Ericeira Surf Guide