You Do Need power plug adapter while traveling from Guyana to San Marino.

Here is Why You Need An Adapter

The outlet and plug type used in San Marino are C, F and L and in Guyana are A, B, D and G. This is how they look like.

Guyana

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

Type A

Type B

Type D

Type G

San Marino

In San Marino, outlets of type C, F and L are in use.

Type C

Type F

Type L