Under compactional stress, methane and related hydrocarbon gases mixed with mud force their way upward and burst through to the surface, spewing mud into a conelike shape. Because of the compactional stress and the depth from which the mixture comes, the mud is often hot and may have an accompanying steam cloud.

Yellowstone is also known for its lakes and rivers, which are stock with fish; especially trout is very popular with anglers. Among these are Yellowstone Lake, Shoshon Lake, and from rivers for example the Snake River, and the Yellowstone River.

Yellowstone Lake has 360 km2 of surface area, maximum depth of 90 m , is 32 km long, and 23 km wide and it lies at 2 356 m above sea level. It is the largest water body in North America at so high an altitude. It is fed and drained by the Yellowstone River. Yellowstone Lake has a shoreline of 175 km and is a really haven for rare species of water birds, for example trumpeter swans or Canadian geese and is prized for trout fishing.

Yellowstone River is well known for its scenic beauty. It rises in Yount Peak in Wyoming. It feeds into Yellowstone Lake below which it plunges 129 m in two spectacular waterfalls and then enters the Grand Canyon of the Yellowstone. The river was first explored in 1806 by Lieutenant William Clark, who sailed it down on his return journey from the Pacific. The firs trading post on the Yellowstone river wax established by Manuel Lisa, an indian trader, at the mouth of the Bighorn River in 1807.

Most of the park is forested, characteric tree is lodgepole pine. In valleys grow sagebrush and rabbit brush, and in warm months you can see wildflowers blossoms in Yellowstone. Unfortunately there was a disastrous series of forest fires in 1988 and large areas of park are burnt out now.

Animal life in Yellowstone is typical of the Rocky Mountains and includes buffalo, elk, deer, moose, bears, and coyotes. Rodents and other small mammals are also common. There are hundreds of different birds' species in the park, among them many waterfowl.

The Yellowstone is a nice place, like mostly all national parks are, but I'm afraid that has no importance. What is the meaning of national parks which cover hardly few per cent of Earth's surface, when the rest of the Earth is continuously destroyed by humans? That could be a good joke. I think that national parks are established mostly for conscience. What will be the meaning of few oases of life amid a destroyed Earth? What I'm really looking forward is the day, when there will be no need for national parks or any other parks, because people will respect and value the nature.