A great fishmonger! From house-smoked trout to seasoned filets to crab-stuffed mushroom caps, everything I've bought from De La Mer has been delicious and remarkably fresh. The service is always really friendly (they've been handing out a lemon "on us" the past few times I've visited) and their suggestions are always helpful.
While I think Roncesvalles would be noticeably short on quality seafood without De La Mer, it doesn't abuse its briny monopoly in any way. A gem for sure!