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

Here is Why You Need An Adapter

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

Martinique

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

Type C

Type D

Type E

Costa Rica

In Costa Rica, outlets of type A and B are in use.

Type A

Type B