Hi, i'm on Stony Creek cave now because my quest marker led me here, but there's nothing here! Is there a secret way to get behind the waterfall or something?

What quest is this?

Lost Relic, trying to find the Dawnguard Rune Hammer. Kagrenzel is the name of the Dwemer ruin that's the destination.

So go there.

The quest marker told me to go into Stony Creek cave, so i did. And i'm stuck! Or are there an alternative way to get there?

yes my brother did this quest, what you have to do is get on a rock near the waterfall, should be higher then the waterfall, then whirlwind sprint

Ahh, i don't have Whirlwind sprint yet, haha. I've only completed Dragon Rising. Oh well, up to High Hrotgar i am then.

The quest marker lies. This is http://www.uesp.net/wiki/Skyrim:Kagrenzel. It EXITS into Stony Creek cave.

Here is the loccation. http://www.uesp.net/maps/srmap/srmap.shtml?centeron=Kagrenzel See Stony Creek Cave to the left? Just head up the mountain North East of the cave. Kagrenzel is up there.

Ohh, thank you. I wasn't quite ready to continue the main quest yet.