You Do Need power plug adapter while traveling from São Tomé and Príncipe 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 São Tomé and Príncipe are C and F. This is how they look like.

In São Tomé and Príncipe, outlets of type C and F are in use.

Type C

Type F

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

Type I

I am from

going to