Hoenn walkthrough section
Pokemon Ruby and Sapphire Phase 3: Route 109 And Slateport Beach
Dynamo Badge Sail from Dewford to Slateport when Steven's letter is delivered. Route 109's beach trainers are optional, but you should clear them for money and experience.
Phase 3 Dynamo Badge Slateport, Route 110, Mauville, Rock Smash, and Wattson. 03 / 10 
Phase 3 section 1 of 6
Sail from Dewford to Slateport when Steven's letter is delivered. Route 109's beach trainers are optional, but you should clear them for money and experience.
Route 109 And Slateport Beach
Sail from Dewford to Slateport when Steven’s letter is delivered. Route 109’s beach trainers are optional, but you should clear them for money and experience. The Seashore House rewards you with Soda Pop after beating the trainers inside. Soda Pop is cost-efficient healing for this point in the game.
Slateport City has a large market, a Pokemon Fan Club, the Name Rater, the Contest Hall, the shipyard, and the Oceanic Museum. The story path is shipyard first, then museum. Talk to Dock in the shipyard so he tells you Captain Stern is at the museum.