Anyone who’s ventured out across the vast, deep-blue, briny sea—on a cruise liner perhaps—has probably entertained what falling in would be like. Our minds conjure visions of “Jaws” lurking, unseen in the black depths, under our dangling feet. But what would you do in that situation, really? One former Royal Marine of the Netherlands has a few survival tips up his sleeves—his pant legs actually—for us in just such a scenario. Dutchman “Robin H,” now living in the United States, has trained in all sorts of survival skills during his stint in the Royal Marines. Now, he demonstrates those ingenious survivalist hacks in lively videos on TikTok, where he’s also gone hugely viral. As for staying afloat lost at sea, Robin teaches how to create a flotation device out of some unlikely materials: your pants. (Courtesy of Robin H) In a video, he demonstrates in a swimming pool, saying, “Your clothing has …