What mammal is known for the loudest vocalization, audible underwater hundreds of miles away?

Blue Whale

In Mexico, what do people traditionally break during Christmas festivities? In Switzerland, which unique calendar marks the countdown to Christmas by opening numbered doors each day? Which Marvel technopath mutant wears goggles and can perceive digital signals? Which President declared war on poverty in the 1960s? What word is used in Christian churches as a greeting on Easter Day?