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I bought them here, https://www.statuecruises.com/ You have to arrive half an hour before, just in case you are late at the security check. But 100% recommended.
Jairo, you have two options. You can buy a City pass, you do it through this page https://es.citypass.com/new-york There you buy passes for various attractions, and you can include the statue. If not, you can buy them directly at the box office. You arrive at Battery Park and there is Castle Clinton, in that place they sell tickets. They cost $ 23.50 and right there you catch the ferry that takes you to the Statue.
Look for the New York pass (blue color), if you are going to be several days it is the best, you can visit several attractions for a good price.
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