You Do Need power plug adapter while traveling from Puerto Rico 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 Puerto Rico are A and B. This is how they look like.

Puerto Rico

In Puerto Rico, outlets of type A and B are in use.

Type A

Type B

Åland Islands

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

Type C

Type F