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

Here is Why You Need An Adapter

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

Cocos (Keeling) Islands

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

Type I

Sint Eustatius

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

Type A

Type B

Type C

Type F