As I write this, I am sailing on a river cruiser called the 'Amadolce' down the Danube River. I am writing (instead of circling the breakfast buffet table for the third time) because I had forgotten that I had a deadline to do anything but have fun and attempt to fill out the waistband of my stretch jeans.
If you have only experienced ocean cruises, you probably do not know how wonderful it can be to sail serenely down a wakeless river through towns and villages, some constructed more than 1,000 years ago, enjoying each stop, visiting the historic sites, sampling the local cuisine and engaging the locals along the way. 
It is an educational journey as much as a vacation. This one on the Danube recalls much of what took place during World War II where the Nazis headquartered in the early days, building Hitler’s youth movement and imprisoning all who dissented at horrible concentration campus such as Dachau.
Life on the ship (never call it a boat or the captain and crew will frown at you,  seriously) is not about bustle or long lines in the buffet, but a camaraderie of fellow passengers who are all most likely within 10 to 15 years of your age. They, too, are empty-nesters. It may come as a disappointment to some of you, but there are no children on board.  While we share our iPhone collection of soccer photos and babies in onesies, no one says, “I just wish I could have brought my grandkids.” For a week, we are the kids... the ones who still live inside us and think nothing of having a second and maybe a third dessert when offered by an enthusiastic waiter. And there are many!
Every night after dinner, we surrender to the music of our youth, and some songs more contemporary, with what can best be described as “wild abandon.” Loosely interpreted, that means we may have had knee surgery two months ago and still cautiously navigate a set of stairs, but we are able to “twist and shout” on the dance floor without pain – at least not at the time.
Last night after dinner, my friends and I joined a group of 20 women, and maybe two men, on the dance floor in a vigorous version of “YMCA,” followed by “I Will Survive” and, ultimately, “The Chicken Dance.” I have never seen teenagers with more energy or enthusiasm.
This morning, after conquering the sumptuous breakfast buffet (again), I saw a single guy I met the day before from Seattle. 
“Will, we missed you last night on the dance floor,” I said.
He looked at me and grinned, “I’m sorry, but I was waiting for you in the Jacuzzi.” Ooh, la la, 16, again.