You cant You need to go to Dewport and surf west to an abandond ship . Find it in their
Oceanic Museum in Slateport City
You can buy TM43 in Slateport City or you can find it Route 111.
staleport city
I find scanner in Abandoned ship. By the way, to get it you need pokemon that can Surf and Dive. After get scanner, head to Slateport City and go to the Harbor. Give it to him, and he'll give you DeepSeaTooth or DeepSeaScale. You may only choose one. If you trade Clamperl while holding DeepSeaTooth or DeepSeaScale, Clamperl will evolve.
Head to slateport city and go to the SS tidal captain stern will be nearby.
You can find a deep sea scale in Slateport City, Captain Stern will give it to you after you give him the Scanner which you can find on the Abandoned Ship.
he's not in there! he's in slasport city his worker is in the abandoned ship and he asks you to find the generator or something i forgot then you have to find it and then you go talk to him and he will tell you to go to captain stern and then go to slaport city and then he will trade you for something. hope i helped :)
You have to talk to the scientist guy at the ship place in slateport city
When you surf near Slateport, you will find an abandoned ship. In that ship, you will get the scanner.
There all in different cities/towns: Verdanturf town, fallarbor town, slateport city, lilycove city.
You have to beat Norman at the Petalburg Gym and the twins at Lilycove Gym to get HM's Surf and Dive. Then, go to the Abandoned Ship (you will see the ship when you ride from Dewford to Slateport on Capt. Briney's ship) and find the scanner. Then, show the scientist on the ship that you have the scanner and he will ask you to deliver it to Capt. Stern who is at the harbor in Slateport. Give him the scanner and in return he will give you either the deepseatooth or deepseascale (which ever you choose).
You go to Slateport and go to the museem and you can find him on the second floor