First, go to Route 1, then use Surf to take you onto the next body of land. Go trough the gate and you're on Route 17. Next, use Surf again, to get to the currents.
Take the bottom current to get to land. Go up the stairs and pass the house, go down the stairs and go north or south. If you go north, go up the stairs and go along the path and you will eventually get to a beach.
Hope this helps!
(If this is not what you mean then please let me know! :)
This video shows you how to get to the area that I believe you are talking about. It's not very high quality, but at least it tells you where to go.