You Do Need power plug adapter while traveling from Bonaire to Cocos (Keeling) Islands.

Here is Why You Need An Adapter

The outlet and plug type used in Cocos (Keeling) 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

Cocos (Keeling) Islands

In Cocos (Keeling) Islands, outlets of type I are in use.

Type I