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

Cayman Islands

In Cayman Islands, 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