I booked this as part of the Land & Sea special package over the phone. Then our cruise got rescheduled to arrive in Catalina a day later, so I called them back and they switched it over for me -- no problem. Very friendly people.
We did have to walk over to the Tour Plaza (very close to dock) and pick up our tickets, and there was only one lady working. We had plenty of time to spare, so walked over by the shops, looked around, then headed back over when the line had gone down.
The semisubmersible boat is very comfortable. Everybody gets their own padded chair and huge window. I would suggest for your party to get chairs across from each other so you can switch windows back & forth if you want. There are LOTS of fish! The guide throws in pellets for them from outside, then comes down to explain which fish you are seeing and answer any questions.
***It's not like the Caribbean -- don't expect to see coral or a huge assortment of different fish. You'll see sea grass, silver / grey colored fish with cool green & blue eyes, and those bright orange Garibaldi fish. And the trip is not long. You don't go far at all. But it was a blast! Everyone comes up above and rides 3 minutes back to the dock out in the fresh air. I would definitely recommend this tour - with or without kids along.