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

Here is Why You Need An Adapter

The outlet and plug type used in Saint Lucia is G 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

Saint Lucia

In Saint Lucia, outlets of type G are in use.

Type G