We take a small squirt bottle. Fill it with water, mist your clothes, then shake a few times to get the wrinkles out. Works best if you can plan ahead on what to wear (so you can let the clothes dry before wearing). Works like a charm and is a cheap alternative that doesn't take up much space in your luggage.
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Carnival Liberty - 2/2007
Carnival Destiny - 4/2004
RCCL Monarch of the Seas - 7/2001
NCL Sunward II - 1982