I also have the national parks pass and this is a separate thing. The cost is $37 per person and it includes the ferry ride the audio tour any guide led tours and the entire trip basically. The biggest thing that I would recommend is that you booked this in advance. I was told the book at 90 days in advance and that was about 40 days before my trip but luckily I was able to still book it. I wouldn't book it less than a month in advance.
I was actually able to book my Alcatraz tickets just 3 days in advance, as I went in February and it was likely a low season. So if you are visiting during low seasons and you don't have every day planned out well in advance, I wouldn't stress too much about the 90 days in advance and just go for it. You can also still buy tickets at the landing. However, I can see how it would be very busy during summer months, so then the 90 days advanced booking would likely matter more!
Can you purchase tour tickets there?
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