How do you want your eggs boiled?
Upper Geyser Basin in Old Faithful area offers 2.7 mi of paved trails, about 3 mi of boardwalks over hydrothermal surface areas and about 1.6 mi of dirt trail going to Old Faithful Observation Point.
Bicycles and wheelchairs are welcome on paved trails, bicycles are not allowed on dirt trails and boardwalks. Human traffic is not allowed to leave established walkways in order not to get burned by boiling water and chemicals contained in it. Bison, elk and other wildlife spending winters in hydrothermal areas must be boiling-resistant, so you can see a lot of evidence of them inhabiting geyser fields in colder months.
Upper Geyser Basin is one of three large geyser basins along the Firehole River and the majority of the world's active geysers are here. Five of six geysers that are predicted by Yellowstone park rangers are located in this area. Predicted eruption times are posted inside Visitor Center (all geysers), in lodges lobbies (Old Faithful), on information boards at geysers themselves.
Check out the Triplogs.
WARNING! Hiking and outdoor related sports can be dangerous. Be responsible and prepare for the trip. Study the area you are entering and plan accordingly. Dress for the current and unexpected weather changes. Take plenty of water. Never go alone. Make an itinerary with your plan(s), route(s), destination(s) and expected return time. Give your itinerary to trusted family and/or friends.