More than 70 percent of the Earth is covered by water and humans have only explored a fraction of it. With waterproof cameras, National Geographic photographers have figured out how to merge our world with the mysterious one below.
To celebrate reaching 100 million followers, we’re resharing a few photos taken at sea level you’ve liked most. Remember to post your best Nat Geo-inspired photos using the hashtag #natgeo100contest for a chance to win a Nat Geo photo safari to Tanzania. Carousel photos by @paulnicklen, @daviddoubilet, @paulnicklen, @thomaspeschak, @jenniferhayesig.