If you are looking for a specific ship, you can google it and it will tell you. I looked it up for quantum of the seas and it is almost 3 laps for a mile. Although I have not run on a Royal Carribean Cruise, I did run 16 miles (in on setting) on the running deck on a Disney ship and it was pretty easy. Easy in the sense that I didn’t really have to avoid people. I have run on NCL and it was pretty easy too. To keep track of the laps on my 16 mile run, I ate a jelly bean for each lap.