score:6
US Citizens don't need a visa and can enter without a passport provided they can show an original or notarised birth certificate to prove their citizenship, and that they have a return or through ticket to a country that will accept them. (Source)
Whilst it might be technically possible to fly without a passport, returning to the US with just a birth certificate might lead to delays at US immigration.
A passport is the way to go.
Upvote:1
As you are presumably a US resident, you can stay for up to 30 days:
Residents of the United States of America
A person resident in the United States of America who:
- arrives in the Cayman Islands directly from that country;
- on landing, produces a valid United States Alien Registration Card; and
- produces a return or round trip ticket to that country,
may be permitted to enter and remain in the Islands for a period not exceeding thirty days.