We did Randi's horses in Mazatlan, when we cruised on the Pride.
At the time, it was $45 per person CASH ONLY (including all transportation from and back to the ship). Check her website...it may have gone up since then...
Randi meets you at the pier. Loads you into the back of a truck...then to a ferry and then onto a wagon to get to the horses on Stone Island.
She repeats the process in reverse to get you back. It was all very safe.
Actual horseback riding was a little over an hour. It is not nose to tail trail riding. You ride on the beach for the most part. You can go as fast or as slow as you wish...as long as you don't lather the horses.
You book a reservation on the Internet. No Credit Card info required to make the reservation.
In PV, hubby and oldest son did the zipline Canopy tour through an independent company called Los De Vernos. Also booked it online without having to give them a credit card. Remember that PV will be an hour off your ship time....so they booked their time at 11:00 and it worked out fine.
The tour was around $75.00 CASH (a surcharge of 5% for using Credit Cards) and a taxi to and from the ship was $3 a per person.
Have a great cruise!!