you dont even want to know......
*whispers* he everywhere........he is watching you 0.o === whoever said this answer is a nuisance because according to this you know the answer and everyone wants to know it! (this add on is from jamesbungay - my username)
It's the Seafloor Cavern... An underwater cave where the legendary pokemon, Kyogre is sleeping.
Once you get the scanner, go to slateport and find captain stern, he will trade you a hold item for it.
Go to the shipyard, and talk to the guy standing by the table with a map on it. He will tell you Captain Stern isn't there. Leave the shipyard, and go into the museum. Go to the backroom, and talk to the scientist. He is Captain Stern. Team Aqua will come inside, and be prepared for two battles. After you beat them, you can give the parts to Capt. Stern. Hope this helps! :)
nasa puso mo
You will need to give the Scanner to Captain Stern in Slateport City. Once you obtain the Clear Bell from him, return to the Abandoned Ship/Sea Mauville and you can encounter Ho-oh at the north-western edge of the ship.
Captain Stern is first located at Slateport City. After saving Mr Briney's Peeko on the tunnel, go to Briney's hut and talk to him. After delivering the goods at Steven and finishing the gym at the Dewford town, talk to Mr. Briney and go to Slateport City. Go up and enter the museum. On the second floor, captain stern was standing next to the scale model of SS Anne.
Capt. Stern is not in Pokemon Leaf Green. He is only in Pokemon Ruby, Saphire or Emerald.
In the slateport city boat dock place
You go to slateport and you deliver the Devon goods to captain stern.
You can either go to the next route or get the exp.share from the president.
While in Lilycove City, you can find Captain Stern in that museum place where Team Magma/Aqua are standing by. I forgot how to get rid of them, but once you do, you can find Captain Stern in that museum place I mentioned.
In the Slateport museum.
It's the Seafloor Cavern... An underwater cave where the legendary pokemon, Kyogre is sleeping.
Once you get the scanner, go to slateport and find captain stern, he will trade you a hold item for it.
Captain Stern is on the top floor of the museum in Slateport City.
Captain Stern will be in the Oceanic Museum. There will be Team Aqua members outside. They will once clear when you go into the shipyard when you will find a man beside a table. Once you talk to him, the Aqua members will be gone and you can enter the Museum for $50. Hope this helps!
south, down the Pokemon beach