Running a half-marathon is hard enough. How about doing it underwater in a river with low visibility?
That’s pretty much what underwater filmmaker Nathalie Lasselin did recently — dive the 13.1 miles/22 km down the St. Lawrence River near Montreal, Canada.

The feat took her about six hours, according to an entry on her Facebook page, where Lasselin wrote:
“In order to achieve this different kind of dive, I had to face many challenges in the low visibility waters so I would not have to surface, But this is not the only challenge. I will write more about it soon and tell you more but in the meantime, I would like to thanks my team and people who helped me. Divers and non divers who, like me, have a concern for the environment, each of them has a specific role.”
For more information, check out Lasselin’s Facebook page or her website at nathalielasselin.com.