You Do Need power plug adapter while traveling from South Africa to Saint Barthélemy.

Here is Why You Need An Adapter

The outlet and plug type used in Saint Barthélemy are C and E and in South Africa are C, M and N. This is how they look like.

South Africa

In South Africa, outlets of type C, M and N are in use.

Type C

Type M

Type N

Saint Barthélemy

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

Type C

Type E