You Do Need power plug adapter while traveling from Pitcairn Islands to Equatorial Guinea.

Here is Why You Need An Adapter

The outlet and plug type used in Equatorial Guinea are C and E and in Pitcairn Islands is I. This is how they look like.

Pitcairn Islands

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

Type I

Equatorial Guinea

In Equatorial Guinea, outlets of type C and E are in use.

Type C

Type E