The width of the span is quite short, so much so that from the front the cliffs on either side appear to touch. Below the cliffs two rocks jut out from either bank, presenting a gate-like appearance.
前面另有兩塊大岩壁，像是向二側拉開的屏風，守護著它。中杭地勢山接水、水接石，經常走到絕處時突然又出現洞天，害得遊人即使行到水窮處，仍不肯相信前頭已經沒路。