I read that in 1918 when they relaxed quarantining after the first wave had passed, NYC held a parade to celebrate, and a week later their hospitals were all overrun again with flu cases. You know what they say about history repeating itself...Yep, then those visitors reseeding their homelands on return. Several days cramped together on those floating resorts can certainly aid in spreading. The 1918 Flu traveled in waves partly with returning WWI service members returned from overseas, but our transportation is much more efficient this century. I'm not expecting waves so much as repeated hot spots and explosions.