Overview

• An anonymous tourist was documented on July 28 walking in flip-flops across protected bacterial mats at Grand Prismatic Spring to retrieve fallen hats.
• A July 30 post in a public Facebook group drove renewed scrutiny of visitor conduct around Yellowstone’s thermal features.
• Thermophile bacterial mats create Grand Prismatic Spring’s vivid colors and are highly sensitive to disturbances.
• Park officials have not announced charges in the latest case but reaffirm that thermal trespassing carries fines, park bans and possible jail sentences.
• Yellowstone has recorded more than 20 fatalities from off-trail thermal injuries, underscoring the importance of boardwalks and warning signs.