Eastern Carribean shore excursions

We would like to do shopping and spend time at a beach at St Maartan and St Thomas/St Johns. I’m having a hard time deciding on an excursion for both islands. I have 3 girls 16, 15, & 10. I have read that it is recommended to book an excursion. It’s hard to know which one to pick. Is it safe to plan it on your own?

Strongly recommend doing it through the cruise line. You pay extra but the peace of mind knowing the ship will wait for you is priceless though St Maarten and St Thomas are usually okay. For St. Thomas, I would do Coral Park with kids that age.

The helmet dive is awesome. There’s a world class beach next to it…Coki Beach, I think.