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

Here is Why You Need An Adapter

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

Sint Eustatius

In Sint Eustatius, outlets of type A, B, C and F are in use.

Type A

Type B

Type C

Type F

Cook Islands

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

Type I