You Do Need power plug adapter while traveling from Saint Barthélemy 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 Saint Barthélemy are C and E. This is how they look like.

Saint Barthélemy

In Saint Barthélemy, outlets of type C and E are in use.

Type C

Type E

Papua New Guinea

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

Type I