On March 19, the fifth day of explorer Eric Larsen's 49-day attempt to trek 500 miles across the Arctic Ocean to the North Pole, he had a polar bear encounter. "I'm not sure we would have seen them in time had we not turned around," Larsen told Men's Journal by text from his satellite phone. "It was a mother and her cub, and they were following us."

Larsen is no stranger to polar bears. He's seen them before in the Arctic, most notably near Russia in 2005 when one jumped on his tent and almost crushed him inside. "They look cute in pictures but in person they're huge, and singularly focused on finding food," Larsen texted.

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During his latest expedition, Larsen and partner Ryan Waters have been on the lookout for polar bear activity. The difference on March 19 was that the bears crept undetected behind them, stalking the half-frozen humans towing 350-pound sleds of food and supplies.

When Larsen and Waters realized the bears were there, they stopped. "But they just kept walking toward us," wrote Waters in a blog dispatch. Both men keep a pencil-sized flare in their pocket during expedition that fires small, but loud, bear bangers up to 50 feet away. It took three flares to stop the bears' continued approach. To drive them away, Larsen pulled out the shotgun and fired a much larger bear banger, which sent them scampering. "We paced off the distance from where we had been to their prints when they finally ran," wrote Waters. "It was 15 feet."

Polar bears are the reason Larsen and Waters pack a Mossberg 500 pistol grip shotgun loaded with large bear bangers, then birdshot, then slugs. "When you're carrying almost two months worth of food and supplies, every piece of gear gets careful consideration, but this one is a no-brainer," Larsen said via sat phone. "In the Arctic, it's the difference between life and death."