You Do Need power plug adapter while traveling from Saint Martin to Guyana.

Here is Why You Need An Adapter

The outlet and plug type used in Guyana are A, B, D and G and in Saint Martin are C and E. This is how they look like.

Saint Martin

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

Type C

Type E

Guyana

In Guyana, outlets of type A, B, D and G are in use.

Type A

Type B

Type D

Type G