Shoshone Geyser Basin is one of Yellowstone's wilder thermal areas, reached by a long backcountry hike rather than a roadside boardwalk. The route crosses the Continental Divide at Grant's Pass before dropping into a basin of geysers and hot springs.
This is not a casual stroll from Old Faithful. Stay on established trails, carry proper backcountry gear, and treat the thermal ground with real caution: crusts can be thin, water can be scalding, and help is a long way away.