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

Here is Why You Need An Adapter

The outlet and plug type used in Cook Islands is I and in Bonaire are A and C. This is how they look like.

Bonaire

In Bonaire, outlets of type A and C are in use.

Type A

Type C

Cook Islands

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

Type I