黄石公园以数量繁多的热喷泉，大小间歇泉，种类繁多的野生动物，绚丽多彩的高山，岩石，峡谷和河流闻名于世。
间歇泉里最有名的自然是“老忠实泉”（ Old Faithful ）了，它从被发现到现在的 100 多年间，很有规律地平均每隔约 90 分钟喷发一次，且从来未让等待的人们失望过而得此名。它每次喷发能持续 1 ~ 5 分钟，水柱高度在 30~55 米之间，每次喷水量为 3700~8400 加仑，依季节不同略有不同。
俺们到达老忠实泉时大约 11:00am ，一边在礼品店转悠一边议论何时喷发时，旁边一讲国语的帅小伙子告诉俺们， 10:45am 刚喷发完，下一次是 12:25 分。
老忠实泉周围有一圈“板凳”，俺们提前 20 多分钟走到那儿，发现那圈“板凳”上早已坐了许多翘首以待的游客，俺们也赶紧找了几个空“板凳”坐下。
这老忠实泉还挺会忽悠人的，先喷出一点小水花，当人们激动不已时，那小水花蹦跶两下后，就偃旗息鼓了，这样忽悠你几次后，忽然一下子水柱直冲蓝色的天空，腾起一片白色的水雾，蔚为壮观！它倒是真没有让俺们失望，但也真不知道它还能坚持多少年？
图1：观看老忠泉喷发的游客。
图2：老忠泉未喷发的时候。
图3：老忠泉正在忽悠游客呢。
图4：老忠泉喷发啦！
图5：最高点？
图6：要歇菜了！
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.
