Close Call: When a Hippo Flips Your Boat

Steve Boyes is a conservation biologist and National Geographic explorer. He is dedicated to the preservation of the Okavango Delta, the last wetland wilderness in Africa. He and his brother, Chris Boyes, led an expedition over 1,500 miles (2,414 kilometers) down the length of the Okavango River in 2015. Bringing together expedition, science, and documentary teams, they made it down the length of the Cuito River—a source river starting in Angola—to the delta’s end in Botswana.

Throughout the expedition, the team behaved in ways that maximized their safety during wildlife encounters. Species in the Okavango River Basin include African bush elephants, lions, hyenas, crocodiles, African buffalo, leopards, and what many consider the most dangerous mammal of them all: the hippopotamus.

Steve Boyes remembers when he made a mistake and didn’t recognize a hippo in the reeds: “We were going as fast as we could down the Cuito River, covering good ground. I heard my brother shout from the back, ‘There's something big coming through the reeds! The reeds are moving! Reeds!’ I had seen crocodiles earlier that morning, and I thought it was a crocodile.” Because he thought it was a crocodile, he aimed to give it a wide berth and went off into the deep water. “In the deep water, as soon as I was there, there was a swirl on the right-hand side, and I started thinking, Now, crocs don't really do that. A second after that, the water kind of lifted on the left-hand side. Something had gone under me, and I called, ‘Kubu! Hippo!’ to the team, trying to warn them. Right then, as I thought it, I see this face coming up. Then it's like a bomb going off.” The hippo hit their canoe, and Boyes and Trevethick went flying. The mokoro [dugout canoe] flipped over. “We swam like nobody had taught us how,” Boyes said, “just arms and legs as fast as you can. The bank was actually quite high. I threw myself up there. I got Giles up. I pulled him off out of the water, and my whole body was just covered in goose bumps. The first thing I did when I realized he was fine and I was fine was give him a big hug … Then we went about the activity of retrieving everything and working with the team to fix what had happened.” Other members of the expedition team hauled the boats out and rescued all of the gear—including their solar batteries, shoes, water bottles, and even their lunch.

“We understand hippos very well and usually have no problem giving them a few minutes to do their thing,” Boyes said. “Hippos are vegetarian. They are defensive animals, and I think the most important thing about them is they are incredibly powerful. That two-ton animal is able to lift its entire body out of the water and crash into you if it feels that's necessary. I feel safe around hippos. I really do. If something happens, it's because I've made a mistake. They have a set of rules that they abide by, and they hardly ever break them.” In fact, they planned their schedule around the hippos. Boyes said, “We don't get into the water before 10 o'clock in the morning because we're waiting for the hippos to get into the pieces of water they want to be in, so we know they're there.” They also navigated their boats to avoid hippos: “Don't go in the deep water. The hippo may be underwater, and you may be going over it. Go in the shallows where a hippo would always be exposed.” Hundreds of times throughout the expedition, they would see a gap in the reeds where a hippo had entered the water, and they would head straight for that spot. “We know they are going to go for the deep water, and then we just go past. [In this case], I thought it was a crocodile. It was much deeper, so the hippo could get into it, and he just looked a lot smaller. I made a mistake.” Boyes said the capsize experience was “absolutely terrifying … I felt incredibly responsible for it. I lived with that for the next six weeks on the expedition. Every single day I would think of it. Hippos are our main concern on that remote river system. I always know that there are ultimate consequences if something goes wrong.” Over the course of the expedition, they saw more than 570 hippos.

Want to learn more?

One of the unique things about this expedition was that the team uploaded data from the field daily via satellite to their website,, and a public API. They wanted to make the data available for anyone to remix, analyze, or visualize the collected information.

There’s also incredible imagery from this specific expedition and their return transects on Instagram.

Botswana’s Okavango Delta was voted in as the planet’s 1,000th UNESCO World Heritage site in 2014.

See more from explorers in the field in the Expedition Raw web series.


PRODUCER/EDITORS: Kaya Ensor and Carolyn Barnwell

VIDEO: Kaya Ensor and Neil Gelinas

SERIES PRODUCERS: Chris Mattle and Jennifer Shoemaker

GRAPHICS: Chris Mattle and Babak Shahbodaghloo