What do you have to have to do to go to whirlpool island on soulsliver?

To access Whirlpool Island in "Soul Silver," you need to have defeated the Elite Four and the Champion at the Pokémon League. After that, obtain the Surf HM (HM03) to navigate water, and then head to the Whirl Islands, which are located between Olivine City and Cianwood City. You will also need to have a Pokémon that knows Surf to reach the islands. Once there, you can explore and encounter various Pokémon, including the legendary Pokémon Lugia.