Question 1

Does an eSIM work on a cruise ship?

Accepted Answer

No. At sea you are on satellite maritime networks, which travel eSIMs do not cover. Your eSIM connects again once you're ashore in a covered country.

Question 2

Do I need a separate eSIM for each Caribbean island?

Accepted Answer

Usually yes, since most islands are separate countries with their own plans. Check for a regional Caribbean plan if you're visiting several.