Valid points. We opted to do several non-cruise corporate sanctioned excursions this past trip to the Western Caribbean on Silhouette (Celebrity). Were we concerned that it was not sanctioned by the TA or cruise line? No, not really. I'm adventurous and spent much time researching our Mayan jungle adventure and snorkeling adventures long before we set sail. I can honestly say that this can offer a splinter-like insight to some.