You Do Need power plug adapter while traveling from Tanzania 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 Tanzania are D and G. This is how they look like.

Tanzania

In Tanzania, outlets of type D and G are in use.

Type D

Type G

Åland Islands

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

Type C

Type F