You Do Need power plug adapter while traveling from Isle of Man 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 Isle of Man are C and G. This is how they look like.

Isle of Man

In Isle of Man, outlets of type C and G are in use.

Type C

Type G

Papua New Guinea

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

Type I