Rio alone, I'm told, has over 70 beaches, each with its own community: Some are for bodybuilders, others are for senior citizens, still others are popular with parents and children.But Rio's beaches are just the starting point for my exploration of Brazil's Atlantic coastline, which at more than 8,000 kilometers (5,000 miles), and with more than 2,000 beaches, is the longest in the world.Every Brazilian has his or her own ideas of the perfect beach and is eager to tell you where to find it.I'm happy to take people's advice, but my ultimate goal is to find my own dream beach.