You Do Need power plug adapter while traveling from Equatorial Guinea 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 Equatorial Guinea are C and E. This is how they look like.

Equatorial Guinea

In Equatorial Guinea, outlets of type C and E are in use.

Type C

Type E

San Marino

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

Type C

Type F

Type L