Ahoy, Jose!
Welcome to the Disney Parks Moms Panel! I had the biggest smile on my face while reading your question. The thought of your little ballerina having the opportunity to watch a Russian Ballet while visiting Russia would be an experience she'd never forget!
It may be possible to combine both activities: seeing the ballet and exploring the city. Once your cruise is paid in full and your
advance booking window opens, you will be able to see the specific hours that each Port Adventure is offered. Schedules are subject to change, but as of right now, your Disney Cruise will be docked in St. Petersburg, Russia from around 8:15 a.m. to 11:30 p.m.
A Night of Russian Ballet currently looks to be roughly a 4-5 hour excursion. If the schedule doesn't change too much, these time frames should allow you the opportunity to debark the ship and explore the city either before your Port Adventure or after!
It also might be a possibility to book a second Port Adventure that focuses on sightseeing. Disney Cruise Line allows Guests to book two Port Adventures so long as the times do not overlap and there is enough time for you and your family to arrive at the designated meeting spot for the second excursion. You'll have a better idea of whether or not this is a possibility once your advance booking window opens and you're able to see the details of each Port Adventure.
Jose, thank you for asking such a great question! I hope both you and your daughter have the opportunity to enjoy the ballet as well as the beauty of St. Petersburg.
Beth