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

Here is Why You Need An Adapter

The outlet and plug type used in Pitcairn Islands is I and in Åland Islands are C and F. This is how they look like.

Åland Islands

In Åland Islands, outlets of type C and F are in use.

Type C

Type F

Pitcairn Islands

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

Type I