Are you referring to the "Playa Urbana" in Madrid Río park?

It's.....not a beach. The park as a whole is very nice an a major improvement to the city. The whole beach project is more of a novelty than anything, though it is nice to stop for a picnic or have a drink on a terrace near there. Kids are always running through the fountain that is there as well, but don't think for a second that it's anything like a beach, even a small pretend one.