Yes, it is held on every cruise. And, on cruises that stop at CC twice, they run it twice.
What is suppose to happen, is on CC day, the runners meet on the stairs leading to Deck 1, and you are met by a cast member that explains the route and runs with you around the island.
For our run, when we got there the first CC day (we were on a double dip), it was rainy and our cast member was feeling "under the weather," so he gave us maps and explained the route, and didn't run with us. It was actually a perfect day to run - overcast, on and off drizzle. There is plenty of water along the way, so I just ran with my iPod. There were no walkkers that day, which I think is because of the weather - only the die hard runners and people that wanted to say the did it (me! - not a die hard runner!) were there.
After it's over, the cast member was waiting for us by the ship, where we were met with a bottle of cold Evian water o drink, and given a purple
DCL plastic beverage bottle, which I use every day when I exercise.
After I got back on the ship and showered and ate breakfast, the sun came out, just in time to go back to CC
I didn't run it the 2nd day, because I felt like the whole process took too long (run, shower, late breakfast = less time relaxing at
Castaway Cay). So, the following 3 days, I went to the gym instead around 6:30-6:45am.