You Do Need power plug adapter while traveling from Eritrea to Papua New Guinea.

Here is Why You Need An Adapter

The outlet and plug type used in Papua New Guinea is I and in Eritrea are C and L. This is how they look like.

Eritrea

In Eritrea, outlets of type C and L are in use.

Type C

Type L

Papua New Guinea

In Papua New Guinea, outlets of type I are in use.

Type I