I obtained the Marsh Badge from Sabrina after I defeated her inside the Saffron City Gym. I went to the local Pokemon Center after that and I healed my injured Pokemon. I swapped Pokemon on the PC as well and then I flew to Fuchsia City. I headed south towards the beach area and I arrived at the coast. I Surfed around on Route 19 and I battled against some Swimmers as I headed towards the Seafoam Islands; my Pokemon gained a lot of experience from those battles, so I couldn't really complain. I arrived at the Seafoam Islands after I defeated all the Swimmers, and I entered the first cavern. I encountered some Pokemon inside, but I ignored them and I headed deeper inside the Seafoam Islands. I reached the bottom of the cavern and I pushed some boulders into holes in order to change the water currents. I then saved.