Please see below, Sapphire Princess to Mexican Riviera, particularly Part 4, which chronicles our excursion on the pirate ship. I think your kids would love it, and they might even be asked to participate in the Pirate show!
winecountrygirl.... In Mazatlan, my sister and cousin missed the excursion to Stone Island Beach Break (lucky for them - it was not great).
However, they got off the ship, took a taxi to El Mercado arts and crafts centre, where they did all kinds of shopping, then went to a nearby beach and enjoyed a lovely afternoon.
Maybe your kids might enjoy that too?