Fire crackled and boomed over the seven Rheinland mountains, echoing like thunder off the mountains of the opposite river bank. We were right in the thick of this dramatically named May festival, aboard a dinner cruise ship from Bonn to Linz and back. Setting off in the early evening, we had many hours of daylight before it eventually became dark a little before 10 p.m. In true German fashion, the fireworks were scheduled to start at ten to thirty minute intervals so that our ride back took us straight from one display into another. The banks of the river were marked with evenly-spaced eerie red lights and a more scattered array of smoky bonfires, camper gatherings, and various town wine festivals. We cruised to the tunes of the DJ of our ship and of the neighboring cruises, as well as the spectators’ oohs and ahhs, the international sounds of firework appreciation.