Page "Grand Prismatic Spring" Paragraph 2

The first records of the spring are from early European explorers and surveyors.

In 1839, a group of fur trappers from the American Fur Company crossed the Midway Geyser Basin and made note of a " boiling lake ", most likely the Grand Prismatic Spring, with a diameter of.

In 1870 the Washburn-Langford-Doane Expedition visited the spring, noting a geyser nearby ( later named Excelsior ).