Stingray Encounter & Chankanaab--enough time?

[ratherbcrzn75]

I will be cruising on the Elation with family ranging in ages from 65 to 6. We'll be in Cozumel from 9 to 4 and I thought Chankanaab would be a good choice for the day since it has a little bit of everything . However, my sister would really like her kids to do the Stingray encounter thru the ship. Has anyone done this excursion thru Carnival? If so, does it leave early enough that we would still have time to take a taxi to Chankanaab for at least a couple of hours? Would be we better off taking a taxi to do Stingray City on our own and then taking a taxi to Chankanaab ? Also, I know the two in our group in their 60s will not want to do the encounter---will they still have to pay?

TIA

Edited April 11, 2014 by ratherbcrzn75