You Do Need power plug adapter while traveling from Saint Lucia 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 Lucia is G. This is how they look like.

Saint Lucia

In Saint Lucia, outlets of type G are in use.

Type G

Guyana

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

Type A

Type B

Type D

Type G