You Do Need power plug adapter while traveling from Papua New Guinea to Isle of Man.

Here is Why You Need An Adapter

The outlet and plug type used in Isle of Man are C and G and in Papua New Guinea is I. This is how they look like.

Papua New Guinea

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

Type I

Isle of Man

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

Type C

Type G