Went on the Catamaran Sail and Snorkel tour with Captain Todd and his great crew. The VIP tour van picked up promptly from the Waikiki hotel. The check in and processing were easy. I was originally scheduled another day and had to cancel and then rescheduled and the staff did that for me without any problem. The crew were friendly and fun, but professional and detailed too.
I upgraded to Snuba and dive master Larry was terrific. He'll make you laugh, but keeps an incredibly watchful eye on all of the divers. If you've always wanted to try SCUBA or just want something more than snorkeling - give it a try! Larry is really patient and will let you adjust to the regulator at your own pace. Once you are comfortable, you'll go 15 - 20 feet below and see things much more closely. The reefs and fish are so beautiful. We didn't get to see turtles unfortunately, but we did see dolphins swimming with us as we were sailing!
For those snorkeling, Matt does a great job leading the group around, showing you interesting spots, and being available in case anyone is tired and needs to be towed back to the boat. He does all that with a great sense of humor and easy low-key style.
Even if you don't want to snorkel or Snuba, the ride on the catamaran is so relaxing it is worth it just to be out on the water. Do take lots of sunscreen and a cover up.
Highly recommend Ko Olina for a fun water excursion while you stay on Oahu!