It's crowded, it's loud, it's standing-room-only. It's seemingly impossible to find, but so worth circling the block. Wear shoes you don't mind getting scuffed. Bottles are cheap and ordered by sweetness (sec = sweet, brut = dry). You must buy two tapas (such as a small sandwich or a plate of cheese) with each purchase of a bottle. Go in the afternoon, have a couple bottles and some great chorizo sandwiches, then take a tipsy stroll down the beach.