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

Here is Why You Need An Adapter

The outlet and plug type used in French Guiana are C, D and E 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

French Guiana

In French Guiana, outlets of type C, D and E are in use.

Type C

Type D

Type E