Pokémon Ruby and Sapphire/S.S. Tidal

After winning the Hoenn League you will be back at your house in Littleroot Town. Your Dad will come to meet you and give you an S.S. Ticket that Mr. Briney has sent as a prize. You can now Visit the Battle Tower through the S.S. Tidal waiting in the Slateport City Harbour.

Lilycove-Slateport
The S.S. Tidal's usual run is between Slateport and Lilycove stations, although it is faster to fly, you can battle quite a few trainers and gain some otherwise unavailable items

Battle Tower
To get to the Battle Tower the first time you must take the S.S. Tidal. Just like the first available option.

Items
Two items are available on the S.S. Tidal, a leftovers and TM 49 (snatch). The TM is found in the top most east door, step inside and talk to the person to get the TM. To see what Snatch does look in the TM guide. Then to get the leftovers, go downstairs and either avoid or battle the trainers. The top western trash can holds the leftovers. To see what leftovers does look in the hold items section.