This doesn't answer your question, but although a lot of people advise to wait until you get there to book to save money, not everyone agrees with that advice (I don't). I guess if you really don't care what you do, and you are very flexible, and/or if you will be on each island for a really long time, maybe that approach works. But I had very specific tours I wanted to do on specific days, so I booked ahead. When we were in the tour operator's shop getting fitted for wetsuits for our excursion, a woman came in, desperately looking for an opening on a Punta Pitt excursion before she had to leave Galapagos. She said she'd already been all over town and everything was booked. Our tour operator advised that she was also booked and the woman left, disappointed. I couldn't help but wonder why, if this particular tour was so important to her, she hadn't booked ahead. Possibly hoping to save a few bucks--a very small percentage of her overall trip? To each their own, of course, but I wanted to let you know what I saw happen. I'd hate for you to miss out on something high on your list.