You Do Need power plug adapter while traveling from Swaziland to Martinique.

Here is Why You Need An Adapter

The outlet and plug type used in Martinique are C, D and E and in Swaziland is M. This is how they look like.

Swaziland

In Swaziland, outlets of type M are in use.

Type M

Martinique

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

Type C

Type D

Type E