south, down the Pokemon beach
well after delivering the letter to steven who's in granite cave you go back to mr stone and tell him. he gives you a pokenav. you then sail to slateport and talk to him there.
Capt. Stern is in front of the Slateport City Harbor being interviewed by TV crews.
You get it in Slateport City, by Capt. Stern. Hope I helped :)
In the slateport city boat dock place
he is in the slateport harbor, right above the Pokemon center
You go to slateport and you deliver the Devon goods to captain stern.
In the Slateport museum.
Once you get the scanner, go to slateport and find captain stern, he will trade you a hold item for it.
Fly to slateport and talk to captn. stern and u should hear Archie: Head Of Team Aqua: hes will say something talk to him fly to then fly to lillycove and go to the Team Aqua hideout and do it Ill show you a Map AND WHEN UR DONE THEY WILL GO AWAY!!!!!!
he is in the laboratory in slateport that has many boats and near the bazaar
Captain Stern is on the top floor of the museum in Slateport City.
Near the SS Tidal in Slateport City.