You Do Need power plug adapter while traveling from Vatican City to Cayman Islands.

Here is Why You Need An Adapter

The outlet and plug type used in Cayman Islands are A and B and in Vatican City are C, F and L. This is how they look like.

Vatican City

In Vatican City, outlets of type C, F and L are in use.

Type C

Type F

Type L

Cayman Islands

In Cayman Islands, outlets of type A and B are in use.

Type A

Type B