The trip to Tulum was one of the highlights of the cruise. We had a very knowledgable and personable guide and - as you saw - the weather was beautiful. (Alright a bit hot and humid, but what do you expect on the Yucatan Penninsular in July?)
For parasailing, my daughter and I both went so she took pix of me and I took pix of her from the boat. W also had a disposable which we took up with us, and I will be adding those pictures as soon as I get a chance to scan them. Also, our underwater cameras were film as well so they will have to be scanned. The others were digital so they could go up so quickly.
No, they wouldn't allow anyone but the parasailers on the boat.