no additional payments are made. The only thing you have to take into account is that to use the Harry Potter train that joins both parks you must buy park to park tickets.
The best option is buy a PARK TO PARK ticket. Witch alowd you use the train to use all atractions. Sorry for my english...
No
No once you're in you only pay for souvenirs food and drinks
If you purchase a (1) park ticket for Universal Studios or a (1) park ticket for Islands of Adventures, you would need to pay for a ticket for the park you didn't initially purchase... There is Harry Potter themed areas in both parks. If you want to see both areas, you need to purchase a ticket for (2) parks.
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