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

Here is Why You Need An Adapter

The outlet and plug type used in Denmark are C, E, F and K 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

Denmark

In Denmark, outlets of type C, E, F and K are in use.

Type C

Type E

Type F

Type K