You Do Need power plug adapter while traveling from Somaliland to Niue.

Here is Why You Need An Adapter

The outlet and plug type used in Niue is I and in Somaliland is G. This is how they look like.

Somaliland

In Somaliland, outlets of type G are in use.

Type G

Niue

In Niue, outlets of type I are in use.

Type I