Yes, it is absolutely worth the cost!! My sister and I booked the royal swim in Chankanaab and it was the best money I ever spent!
You are in the water with the dophins for about 45 mins, you will get a dolphin kiss, hold a pole for the dolphins to jump over, hitch a ride by holding their doral fins and the most fun, the foot push, having two dophins push you up and out of the water by the soles of your feet! These mammals are very gentle and you will be amazed at how powerful they are.
We booked our excursion through Princess, it cost $149 p/p, this did include the cab ride to and from the cruise pier, it did not include the $10 admission fee to Chankanaab.
If you have time after your swim, take a walk around Chankanaab, it is beautiful!
I would highly recommend this excursion!
Rose