Hapless Yellowstone tourist finds out just how slippery wet rocks really are

Lakes, rivers and waterfalls offer some spectacular hiking opportunities, particularly during the summer, but don't make the same mistake as this hiker at Yellowstone National Park, who discovered the hard way just how slippery wet rocks can be.

In a video shared this week via Instagram account TouronsOfYellowstone (which you can see below), a woman can be seen slowly sliding down a slick bank into a lake, unable to grip anything to stop her descent. It's not clear why she wandered onto the wet stone, but with only flip-flops for footwear, she is unable to get any purchase on the slippery ground (our guide can you go hiking in flip-flops explains why this is a bad idea).

The dangers of straying too close to Yellowstone's thermal pools are well publicized, but falling into a lake can also be extremely serious. Yellowstone Lake in particular is cold all year round, with an average temperature of just 41°F (5°C). In such cold water, a person is only likely to survive for 20-30 minutes.

"More than 100 people have died in Yellowstone’s lakes and rivers," says the National Park Service. "Cold water makes hypothermia a year-round risk, and spring snow melt makes rivers dangerous to cross."

To keep yourself safe around water, make sure you stick to established trails and don't be tempted to get closer to the water for a better look. Erosion can cause steep drop-offs around bodies of water, and banks can be surprisingly soft or slick. Also make sure you wear proper hiking boots or hiking shoes with deep treads (our roundup of the best hiking boots includes lots of lightweight options that will work well for summer adventures).

Water safety

Crossing rivers is best avoided if possible – even relatively shallow water can be powerful enough to knock you off your feet. If there's no bridge or other way across, and you've checked your map to be sure you've not missed anything, consider the width, speed, and depth of the river, the visibility and appearance of the riverbed (you don't want to get stuck or tangled in anything), and any potential hazards downstream that you may be swept towards. Depending where you are, you may also need to think about whether there might be wildlife like crocodiles and alligators in the area.

If you must cross, look for an area where the water is shallow and slow-moving. It might be tempting to look for the narrowest point, but the water here is likely to be deeper and faster-moving.

For more advice, check out our article how to cross a river safely – and when not to .

• The best water shoes : footwear for aquatic adventures tested and rated