Ecological Tours - Shark/Ray/Caye Caulker

My husband and I are going to be in Belize in mid January with Carnival Cruise Line. It's actually going to be his birthday on the day that we are here and is the only day we'd like to do some sort of shore excursion so we'd looking for it to really be amazing. He really wants to snorkel so that's a definite. I've read some of the reviews here and it seems like Ecological Tours has a good reputation. I've never booked directly with the vendor before and being a bit of a nervous person, it worries me that we won't make it back to the ship on time.

Has anyone done the Shark/Ray snorkelling with Caye Caulker Beach through them before?

Do you know if there is a guarantee that you will get back to the ship on time? Also is transportation back from Caye Caulker Beach included or do we have to find out own way back to the pier?

Any reviews or recommendations would be much appreciated. I'd like to avoid booking directly with Carnival if at all possible but for my own peace of mind, I might end up doing that.

We did and it was totally worth it!