From Portorož bus to Ljubljana bus station then bus to Zagreb bus station. 5hrs 14min 24€. From Portorož bus to Ljubljana then train to Zagreb Glavni Kolod.. 5hrs 20min 23€. From Portoroz bus to Poreč then bus to Zagreb. 5hrs 50min 34€. From Portorož drive to Zagreb - Centar. 2hrs 33min 42€.