Where is the ferry inlillycove on Pokemon sapphire?

it is in the small White House with the lines and the door is open with a red line on top of it.of course you have to beat the champion to ride inside of it.it is cool you have a cabin you can rest in and you can only get inside of it by going to slateport and lilycove city.if you go to battle tower you will not go inside you will only go there really fast like the hm move fly.that is all! oh and the roof is red ALL red with ripples(or you can say lines)on top of it.it is in the far corner in the left side