This place needs a BIG swell. When the Linha (the beaches between Cascais and Carcavelos) are too big to surf (3m+), this is pretty much the only place that will hold the swell. If you are confident, you can jump into the peak from the rocks in front of the castle, but make sure you time it right or you'll be washed back up onto them. It's a heavy, fast and often hollow wave which will be populated by the best surfers in Portugal, so make sure you let them have their waves. Also watch out for the recently-constructed groyne, which can actually interfere with the later sections of the smaller waves. Bascially, GO BIG and don't stop. This can be one of the best waves in Portugal when it is on.
Directions: When driving from Cascais direction, after Carcavelos take the turning off the Marginal (coastal road between Cascais and Lisbon) for Oeiras. As you come around the bend on the exit road, there is a car park on the left. Park there and follow the pedestrian path to the left in front of the castle. In Summer, you will see a lagoon, so best to come between September-March when the Winter swell rolls in. Even then, it doesn't