Please help!

If I'm thinking of the right place, you mean a hole in the cliffside that's just off from the entrance to the Ice Cavern?

If so, I think there's a ladder around there somewhere that'll allow you to climb up there.

Yeah, the entrance is underneath this rock in this picture.

I had to use a levitate cheat to get up to the hole, to see how the heck to get in there, and it turns out that the way in is under the above rock, I assume it can either:

a) Be broken with the Megaton hammer as an adult.
b) Not be broken at all, and is a leftover area from the beta version of the game.

When I went up there, I didn't see anything in there, its just a gap in the wall, with a ladder leading down to a corridor which you have to fall into from a small, square hole underneath that rock.

Hope that helped.

Edit: After doing some more experimenting as adult Link, I have determined that breaking that rock is not possible. However, going back up I did notice Navi turned green, perhaps you use the Scarecrow's Song to get up there? But even so, the square hole underneath the rock is intriguing, perhaps it was originally planned to be a way in, but was blocked off in the final release... Strange...

Edit 2: Nevermind, turns out you can lift the boulder up as Adult Link once you have the silver gauntlets... You really do learn something new every time you play this game.