You Do Need power plug adapter while traveling from Aruba to Cook Islands.

Here is Why You Need An Adapter

The outlet and plug type used in Cook Islands is I and in Aruba are A, B and F. This is how they look like.

Aruba

In Aruba, outlets of type A, B and F are in use.

Type A

Type B

Type F

Cook Islands

In Cook Islands, outlets of type I are in use.

Type I