I don't know about age requirements, but you will need a letter from your parents stating you are allowed to travel without them. *If* you are a child, that is....
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Most lines require that you be 21 yrs old. Some allow you to do so at 18yrs. Of the lines that require 21 yrs they have been making exceptions for married people but please check as they have in the past said no even to married couples under 21.