Welcome aboard, Shannon!
Disney Cruise Line offers many different Port Adventure options in each port. There are currently over 40 different adventures in Cozumel alone! Once your window for online booking opens during your online check-in time (75 days prior to sailing for first time guests), you will be able to log into your reservation online and select your Port Adventures. It is then that you will see the specific times for the tours. There are opportunities to partake in more than one adventure, however it depends on which adventures you choose and their specific departure times during your particular sailing. Before you can book those, get an idea of which Port Adventures you are considering by reading about them on Disney Cruise Line's website.
Something you may not realize is that many of the Port Adventures incorporate a few different adventures or popular locales in one trip. Adventures like
Cozumel Ruins and Beach Tour or
Dune Buggy and Beach Snorkel Combo actually allow guests to experience more than one activity within the same adventure. But, many guests love to take part in two adventures in one port, and can easily do both by viewing the times online and choosing two that will work well together. The website will not allow you to choose two that overlap, so that helps in planning as well. Some tours will offer two different times from which to choose for the same adventure, giving you more options as well.
Please stop back with any other questions you might have as you continue to plan, Shannon! I'm happy to help!