In 2026, "Park Hopping" is technically subject to availability, but it is extremely rare for a park to "fill up" to the point where hopping is prohibited. Since the return of "All-Day Park Hopping" in early 2026, guests with a valid Park Hopper ticket or Magic Key can cross between Disneyland and California Adventure (or the four Disney World parks) at any time. The only time you might be denied entry to your second park is during "Phase 4" capacity closures, which typically only happen on the busiest days of the year, such as Christmas Day, New Year's Eve, or July 4th. If a park reaches maximum capacity, Disney will send a push notification through the My Disney Experience or Disneyland app to alert guests. For 99% of travel dates, however, once you have entered your first "reserved" park of the day, you are guaranteed the ability to hop to any other park for the remainder of the day without needing an additional reservation.