The Grand Canyon's Most Poisonous Water Is An Enticing Gourd-Shaped Natural Spring

As one of the Seven Natural Wonders of the World, Arizona's Grand Canyon is one of the most popular national parks in the United States. Visitors might ponder the ultimate time of year to plan a trip to the Grand Canyon, or whether to attempt the Bright Angel Trail, which is considered one of the most dangerous hikes in America. Hidden deep at the bottom of the 227-mile-long and 10-mile wide canyon along the banks of the Colorado River is a natural bright orange-colored limestone spring filled with highly poisonous green waters. Pumpkin Spring is aptly named because it is indeed round and shaped like a pumpkin complete with unique descending stripes on its sides, which were formed by mineral deposits.

It operates as a heated geothermal mineral hot spring, and its single pool is encircled by a travertine that has formed. It's also slowly getting taller as the Colorado River cuts deeper into the Grand Canyon. The water at Pumpkin Spring may appear to look fine on its surface, but it's deeply toxic. Testing of the waters found in the pumpkin-shaped bowl has shown that 1 liter contains about 1,100 milligrams of arsenic. Since 140 to 1,400 milligrams of arsenic is enough to kill an average adult, it's best to proceed with caution around the pool. Additionally, the waters contain other potentially harmful minerals such as lead, zinc, and copper. It's still a sight worth seeing within the Grand Canyon National Park that ambitious adventurers can find their way to if they want to take a peek at this uniquely formed natural wonder.

You'll find Pumpkin Spring near mile 212.9 on the banks of the Colorado River, and its remote location at the bottom of the Grand Canyon means that you can only access it by boat. If you want to catch a glimpse of this wonderous phenomenon, you'll need a sense of adventure and help from a guide to get there. Your best bet will be to book a rafting excursion from one of the outfitters in the Grand Canyon. These trips of varying lengths can travel the entire 188-mile length of the Colorado River. Western River Expeditions is one option, which features Pumpkin Spring on a three day itinerary and a full seven-day one. 

Their trips are offered seasonally April through September, and feature a mix of whitewater rafting and calm river floating, with camping included. The website AllTrips.com, which manages the AllGrandCanyon.com site, also has options for booking rafting excursions that include Pumpkin Spring and provides a general booking number. If glamping is more your style, check out Under Canvas Grand Canyon, where you can snooze in a safari tent right beside the Grand Canyon. Though, be aware that if you go this route, you won't get a close look at Pumpkin Spring.

Given the remote location and toxic waters of Pumpkin Spring, it might be a challenge to find what to do there. Unlike Arizona Hot Springs, which are located on a trail hidden along the Colorado River and known as America's "best natural hot springs," it's not going to be safe to bathe in the 73 degree Fahrenheit hot spring waters at Pumpkin Spring. It's also not advisable to swim in or even touch the waters — and drinking from the pool is out of the question. If you've already been adventurous enough to get there, that's a great first step, and if you've got your camera or smartphone on board, you're going to want to take the opportunity to snap a photograph that very few others get.

The Travel notes that if you're daring enough, climbing up to the top of the pool and taking an easy cliff jump off of it is one attraction at Pumpkin Spring. Cliff diving from Pumpkin Spring is something also shared by author Dave Pennells on the AFS Intercultural Travel Guide about Pumpkin Spring, where he also described the water's color as that of "a 1970s shag carpet." Both reviews came with the same warning and caveat: Be careful not to ingest the water. So, use caution if you're going this route. You can also just simply marvel at nature's creation on a break from a rigorous rafting exploration inside one of America's greatest treasures, the Grand Canyon.