Ahoy Mary Ellen!
I'm excited to hear you will be setting sail on the spectacular Disney Wonder in just a few weeks! I'm sure you are looking forward to a relaxing vacation in the warmer temperatures!
I wish I had better news for you, but unfortunately the fitness center is only for Guests 18 or over. As someone who likes to stay in my normal exercise routine, I'm sure this isn't the news you were hoping to hear. If your girls enjoy jogging, there is a walking/ jogging track on Deck Four. Two and a half trips around equals one mile, and you can't beat the stunning oceanviews. If your cruise stops in Castaway Cay, there is 5K that your family can run together in the morning, and there is also a lot of recreational fun on the teen beach as well.
The Wide World of Sports Deck is another great place to get some exercise while onboard so be sure your girls check it out.
Thanks for stopping by with your question, Mary Ellen. If you think of any other last minute questions, please let me know!
Have a magical day and bon voyage!
Nancy