One thing I remember, you need to call at least 2 days before to reserve a ticket. You don't need to pay until you get there. The building for the tickets is close to the dock AND the boat did leave on time exactly.

We did the whole tour and the only bad thing was I wanted to spend more time at the lighthouse. We did get to climb up to the trap door of the lantern room. There is a day just for the lighthouse tour, but I don't think it is as often.