Five tourists avoided serious injury when the vehicle they were in plunged into a thermal feature in Yellowstone National Park. A wrecker pulled the rig out Friday/NPS

Five visitors to Yellowstone National Park escaped with non-life-threatening injuries when the car they were riding in went off the Grand Loop Road and sank into an acidic thermal feature near Roaring Mountain.

The five managed to get out of the rig on their own and were taken to a nearby hospital following the incident on Thursday morning, a park release said Friday. 

There was no immediate explanation from the park for how the sport utility vehicle left the road and plunged into Semi-Centennial Geyser, a warm pool of water that was said to have erupted with a 300-foot-high geyser in 1922.

NPS photo

On Friday law enforcement rangers from the park shut down both lanes of traffic so a local tow truck could pull the vehicle, which was completely submerged in the 9-foot deep pool, out of the water.

According to the fifth edition of The Geysers of Yellowstone by T. Scott Bryan, the thermal feature was first noticed in 1918 when there was a muddy eruption that spouted about 50 feet into the air.

"However, it was on August 14, 1922, the year of Yellowstone's 50th anniversity, when Semi-Centennial Geyser gained widespread notice," wrote Bryan. "The initial eruption was said to reach 300 feet high. The flood of rocky, muddy water washed out the road and killed trees as far as several hundred feet away."

While there were several other eruptions that year, according to Bryan, the feature has been dormant since the end of that year.

According to the park release sent Friday, the "thermal feature has acidic and hot surface water temperatures (ranging around 105° Fahrenheit)."