If my memory is correct nothing is needed to enter the Blackthorn Gym.
There is no ship in Blackthorn City.
the blackthorn city is in the very north east city
After you beat the gym leader in Blackthorn city. She will tell you to go there.
In the gym at the end of blackthorn city, of course.
Once you defeat Team Rocket in the Goldenrod City Radio Tower and make it through the Ice Path, you are allowed to enter Blackthorn City Gym.
In Pokemon sousilver (I don't know about heart gold )you go to blackthorn city which is located in blackthorn city right across the blackthorn city's gym.
its on blackthorn city
Nope, you cannot dig into or through anything in order to reach Blackthorn City, you have to go through the Ice Path in order to reach Blackthorn City.
You don't unlock, Blackthorn city. You go through the Ice path and then your there.
u have to go to the radio tower in goldenrod city then u can go to blackthorn city from mahogany town
you just go north of blackthorn city and beat the gym leader
Blackthorn City is a location in the game Pokemon Gold. To get there, you have to go through the Ice Path.