Final answer:
The interjection in the sentence is 'Wow'. It expresses surprise at the idea of going on a seven-day cruise.
Step-by-step explanation:
The interjection in the sentence is Wow. An interjection is a word or phrase that expresses strong emotion or surprise. In this sentence, 'Wow' is the interjection as it expresses surprise at the idea of going on a seven-day cruise.
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