We debated taking the full day trip and chose to go with the half day instead - our table mates went with the full day trip and it was amazing and they had a wonderful time. I think they were the only people on thier boat and Capt. Marvins knows what times the tenders leave. They had no problem with getting back ontime. I could kick myself for not going for the entire day. They had a beautiful lunch and beach stop. It would be my choice for Grand Cayman in the future, unless I wanted to fit some horseback riding in as well. You can ask them about timing when you book it. Capt. Marvin's was my favorite activity on our entire cruise.
Karyn