I believe both are 18 in Nassau. Onboard the Magic/Wonder drinking age is always 21.
This is the from the U.S. CONSULTATE WEBSITE:
The legal age in the Bahamas for consumption of alcoholic beverages is 18. Parents should be aware, however, that enforcement of the drinking age is weak. It is easy for teenagers to obtain alcoholic beverages and underage drinking is prevalent. Many of the arrests, accidents and violent crimes suffered by U.S. citizens in The Bahamas involve alcohol.
Here is a link to the website. It has a bunch of useful info and advises about the the crime in the area.
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