If you swim backwards you will be able to get through easier. Use your character with best athletics. Don't miss the tunnel on the other side of the river, too.

I have gone in to the dragonshire cave and deactivated the bronze firebeast and have been going round caves and killed beasts but i don't see the dragon or the gnome and now i am caught between the waterfall and don't know to push the two rocks to get to the chest behind it
Please help