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

Here is Why You Need An Adapter

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

Mauritania

In Mauritania, outlets of type C are in use.

Type C

Martinique

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

Type C

Type D

Type E