What happens after you catch all the unown in pokemon soul silver?

so i went to the alp ruins or whatever its called, looking for something to do. i figured out the kabuto and aerodactyl puzzles, some guy gave me the unown report, so far i have about 11 different types. im not too sure how many different unowns there are but im guessing the entire alphabet. now, after you get out of the unown room, you come up and there is a body of water below it, where you cross to get to the aerodactyl puzzle, there is another section where u jump off the ledge but how do you get to that side?