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

Here is Why You Need An Adapter

The outlet and plug type used in Åland Islands are C and F and in Northern Ireland is G. This is how they look like.

Northern Ireland

In Northern Ireland, outlets of type G are in use.

Type G

Åland Islands

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

Type C

Type F