Discount ticket books are available for purchase at the front gate (not online). They are $400 for 40 tickets good for 20 regular or 40 youth/senior admissions.
You can purchase daily tickets up to 10 days in advance.
All daily tickets must be purchased in advance through this website (i.e. no tickets will be available on-site). When the daily allocation has been sold, no further admission will be permitted on that day.