You Do Need power plug adapter while traveling from United States Virgin Islands 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 United States Virgin Islands are A and B. This is how they look like.

United States Virgin Islands

In United States Virgin Islands, outlets of type A and B are in use.

Type A

Type B

French Guiana

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

Type C

Type D

Type E