RIO DE JANEIRO-With 2012 well un­der way and the Rio sum­mer sun turn­ing up the heat on the streets, the count­down to Car­ni­val has be­gun in earnest. With just weeks to go, a mas­sive street par­ty in the Praça XV marked the un­of­fi­cial open­ing of Rio's Car­ni­val sea­son, giv­ing rev­ellers a sneak pre­view of the most de­mo­c­ra­t­ic and he­do­nis­tic of Car­ni­val's tra­di­tions-the "blo­co." Blo­co is the term used to de­scribe pageant groups that pa­rade through the streets all over the city at Car­ni­val time, singing, play­ing sam­ba mu­sic and danc­ing in cos­tume, gath­er­ing huge crowds of some­times tens of thou­sands of par­ty go­ers in their wake. The idea of the blo­co was first dreamed up in the late 19th Cen­tu­ry in protest against the lav­ish balls and dances thrown by the up­per class­es. The tra­di­tion has since flour­ished and the re­sult is pro­lif­er­a­tion of vast street par­ties that be­gin long be­fore the of­fi­cial start of Car­ni­val and stretch on through un­til the end of Feb­ru­ary.

To­tal­ly free and open to all, Rio's blo­cos are not for the faint of heart. Once a par­ty has been sanc­tioned, vir­tu­al­ly any­thing goes. Streets are blocked off and trans­port grinds to a halt. Beer and frozen caipir­in­has are the or­der of the day, and fan­ta­sy dress is the norm. Rov­ing Lothar­ios abound-both male and fe­male-which can ei­ther be a bonus or a nui­sance de­pend­ing on your stand­point. And de­spite the city's best ef­forts, toi­lets are of­ten in short sup­ply. How­ev­er, for many Car­i­o­cas and Rio res­i­dents the blo­cos are the true heart of Car­ni­val, and make up the ma­jor­i­ty of the cel­e­bra­tions. Deb­o­ra Aran­ha, a Car­i­o­ca liv­ing in Jacarepagu&aa­cute; says she usu­al­ly goes to 15 each year: "Con­sid­er­ing Sat­ur­day, Sun­day, Mon­day, Tues­day and Wednes­day as Car­ni­val (five days), we go to three blo­cos per day."

Ri­o­tur, the Mu­nic­i­pal Sec­re­tary of Tourism for Rio, re­ceived re­quests for 476 blo­cos for 2012, more than were re­quest­ed in 2011, of which 424 were ap­proved. From last year's re­quests, there was a de­crease in ac­cep­tance from 173 to 162 in Zona Sul, 48 to 43 in Greater Ti­ju­ca, and 44 to 41 in Bar­ra da Ti­ju­ca. A full sched­ule can be found at Ri­o­tur's Web site (Rio's of­fi­cial tourism agency) where you can search by neigh­bour­hood or date, or sim­ply plug in the name of the blo­co you want to at­tend. Al­ter­na­tive­ly, apps are avail­able for both iPhone and an­droid to help keep your blo­co sched­ule at your fin­ger­tips.