You Do Need power plug adapter while traveling from Balearic Islands to El Salvador.

Here is Why You Need An Adapter

The outlet and plug type used in El Salvador are A and B and in Balearic Islands are C and F. This is how they look like.

Balearic Islands

In Balearic Islands, outlets of type C and F are in use.

Type C

Type F

El Salvador

In El Salvador, outlets of type A and B are in use.

Type A

Type B