Is it haram for girls to travel alone/with friends?

My parents have always been very strict on me I have only been allowed to go to school and home. I am only allowed to go to cafes and the mall with fiends, I have to ask 2 days before, and be home before 6 pm.

I am 20 years old now and living under this much control as an adult is very frustrating, I am seeing my friends travel while I’m not allowed to do the simplest of things. Unfortunately my parents are not reasonable so without their permission I am planning a trip to Amsterdam for winter break with my friend.

My dad has always looked down on Muslim women who traveled, even if it was for school or work saying they need a mahram. But I’ve also seen opinions that it depends on whether or not it’s safe.

Is it haram to for women to travel without a mahram? When I’m back he’s obviously going to say this excuse and if it’s not true I want to be able to tell him that no that’s not true and explain to him.