Yes, go to Pewter Town, and speak to the old man in the bottom right hand corner. He'll give you a Silver Wing: without it, you won't see Lugia.
Sail down from Olivine City to the Whirl islands, and go to the North Eastern Island. You'll need Whirlpool to get through the whirlpool blocking the entry: surf and walk to the cave entrance, and go in. Use Flash to light the cave up: you could try blundering about in the dark, if you prefer :cheeky: but I like to where I'm going! :cheeky:
From the entrance, walk up to the top wall, turnright and carry on over two ledges. When you reach the rar right wall, go up until you see a ladder. Go down this.
You'll come out on a raised plinth in a massive hall. Stay on the raised area, walk down until you see a left turn, take this until you come across another ladder on the plinth. Use this.
You'll come out into a large room, with a tall waterfall and several pieces of dry land. Surf to, and go down the waterfall. There is a patch of land on the left side of bottom of the fall. this bit of land has a doorway in it. Land here and go through the door. You will now be standing inside Lugia's chamber.
Go catch and good luck!