1. Obtain the Dive Ball:
* After defeating the 7th Gym Leader, you'll obtain the Dive Ball from Steven in Slateport City.
2. Obtain the Dive Pokemon:
* You have two options:
* Catch a Pokemon: Catch a Wailmer or Wailord in the ocean.
* Trade: Trade with someone to obtain a Wailmer or Wailord that knows the move Dive.
3. Learn Dive:
* If you caught a Wailmer or Wailord that doesn't know Dive, you can teach it the move using a TM47 or HM07, which can be found in various locations in the game.
4. Access the Dive Locations:
* With your Dive Pokemon ready, you can now explore the underwater areas:
* Seafloor Cavern: Located in the south of Slateport City.
* Underwater routes: These are accessible from various places throughout the Hoenn region, including:
* Route 134
* Route 135
* Route 136
* Route 137
* Route 138
* Route 139
5. Find the Last Gym Leader:
* The 8th Gym Leader, Wallace, is located at the Sootopolis City Gym. You need to use Dive to access the Gym's interior.
6. Beat Wallace:
* Wallace is a powerful trainer specializing in Water-type Pokemon. Prepare your team accordingly!
Tips:
* Make sure you have a good amount of Poké Balls to catch any new Pokémon you encounter underwater.
* Don't forget to heal your Pokémon regularly.
* Use a Dive Ball to increase your chances of catching underwater Pokémon.
* Keep in mind that underwater battles are slightly different.
Note: This guide is specific to Pokémon Emerald. The process might vary slightly in other Pokémon games.