Is there anyone who has gone to mirage island?

Well this island can only be seen only one way, but it's complicated. A random ID number is chosen every day(on Emerald)and it changes at the end of the day. An ID number of a Pokemon that is in your party must match the islands number. Its right of Pacifidlog town and instead of surfing you must do this.

*Go to Pacifidlog
*Go to bottom right house
*Talk to the man by the window

If he says that he can't see it, then you'll have to keep trying. If he says he can, then go and surf to it.

It's fairly basic in appearance.It's got grass and a berry tree which holds the rare Leichi berry. In the grass you can only find Whynaut.

P.S. I don't know if it's just my game, but if you use itemfinder, you can find more Master Balls.(It's not a glitch)

I havent been there myself, but this is how you do.
Mirage Island is assigned a random hex number each day, (a six digit number)

Each Pokemon in your party is also assinged a number, this number changes everytime you deposit or withdraw the Pokemon, when you go to the mans house in Pacifidlog Town, he checks to see if the number of any Pokemon in your party matches exactly with the number assinged to Mirage island that day.

What do you do there?
There is really not much to do there, you can pick the rare Leichi berry, which is used to make Gold pokeblocks and also raises the attack of your Pokemon when it's HP dips low. Also the only Pokemon that is availible there is Wynaut, lv.5-50.

I'm not sure I havent been there

I have not gone there,but it show's up only at certian times so you never know when you can go there.

1) Mirage Island apears randomly. The easiest way to get there is to use a cheat device.

2) You could find some lechie (sorry if spelled wrong). It's a rare berry! And some beldum and other pokemon.