How do you get to sunyshore city in pokemon diamond

Question

a guy is blocking me

Answer 1

Good thing I'm playing it over again.

What you have to do is, after you've beaten the 7th Gym Leader and head to Acuity Lakefront and battle members of Team Galactic (I don't really care about their name). Once you defeat the commander, you have to head to Mt. Coronet via Oreburgh/Hearthome entrance and make your way to the top battling Team G. Once you defeat them and fight the game's legendary Pokemon, then you can continue to Sunyshore City.