Porkkalanniemen Rantakalliot (coastal cliffs) is known for its stunning coastal views and diverse ecosystems with lot's of wildlife. There's many different nature trails you can walk around while enjoying the beautiful coast and forests. The area has many official places where you can pitch your tent, just remember to not leave any thrash around and don't make a fire in the fireplaces if there is a fire warning in place.
You can leave your car at "Porkkalanportti" parking spot on google maps and start exploring from there.