I had seen posts about Mark's Tours on this Board and contacted him through his facebook page. Mark is very responsive and flexible. We had a group of 13, ranging in age from 4-70. We chose the Blue Hole tour from Ocho Rios and it's one of the best excursions we have ever had.
When we arrived at Ocho Rios, we asked one of the port attendants who called Mark and had him come meet us. Mark was very friendly and knowledgeable. We drove maybe 20 minutes or so to the Blue Hole where Mark set us up with an incredible guide for our hike and swimming/jumping. The kids had a blast and even the 70-year-olds did some of the cliff jumps into the Blue Hole. An amazing experience!
After the Blue hole, we had lunch and then some of the party returned to the ship while Mark took the rest of us shopping.
Overall, I can't recommend Mark's Tours enough. Everything was very clean and safe and well organized. I would do it again in a heartbeat!