黃石公園以數量繁多的熱噴泉，大小間歇泉，種類繁多的野生動物，絢麗多彩的高山，岩石，峽穀和河流聞名於世。

        間歇泉裏最有名的自然是“老忠實泉”（ Old Faithful ）了，它從被發現到現在的 100 多年間，很有規律地平均每隔約 90 分鍾噴發一次，且從來未讓等待的人們失望過而得此名。它每次噴發能持續 1 ~ 5 分鍾，水柱高度在 30~55 米之間，每次噴水量為 3700~8400 加侖，依季節不同略有不同。

        俺們到達老忠實泉時大約 11:00am ，一邊在禮品店轉悠一邊議論何時噴發時，旁邊一講國語的帥小夥子告訴俺們， 10:45am 剛噴發完，下一次是 12:25 分。

        老忠實泉周圍有一圈“板凳”，俺們提前 20 多分鍾走到那兒，發現那圈“板凳”上早已坐了許多翹首以待的遊客，俺們也趕緊找了幾個空“板凳”坐下。

        這老忠實泉還挺會忽悠人的，先噴出一點小水花，當人們激動不已時，那小水花蹦躂兩下後，就偃旗息鼓了，這樣忽悠你幾次後，忽然一下子水柱直衝藍色的天空，騰起一片白色的水霧，蔚為壯觀！它倒是真沒有讓俺們失望，但也真不知道它還能堅持多少年？

圖1：觀看老忠泉噴發的遊客。


圖2：老忠泉未噴發的時候。


圖3：老忠泉正在忽悠遊客呢。


圖4：老忠泉噴發啦！


圖5：最高點？


圖6：要歇菜了！

Old Faithful Area:  

• Old Faithful is in the Upper Geyer Basin, one of three large geyser basins along the Firehole River.
•  The majority of the world’s active geysers are here.
• Only three other locations in the world – Iceland, New Zealand, and Kamchatka (Siberia) – have large concentrations of hydrothermal features.
• Five geysers – Old Faithful, Castle, Grand, Daisy, and Riverside – are predicted by the rangers.
• Old Faithful erupts more frequently than any of the other big geysers, although it is not the largest or most regular geyser in the park. Its average interval between eruptions is about 90 minutes, varying from 51 ~ 120 minutes. An eruption lasts 1 ½ to 5 minutes, expels 3,700 ~ 8,400 gallons of boiling water, and reaches a height of 106 ~ 184 feet (30 ~ 55m). Members of the Washburn Expedition of 1870 named this geyser for its consistent performance. Although its average interval has lengthened, Old Faithful is as spectacular as it was a century ago.