While scientists, explorers, and Google Earth have mapped much of the terrestrial world, the expanses of the sea remain a great mystery. Marine biologist Alexander Semenov , head of the dive team at Moscow State University’s White Sea Biological Station, has dedicated his career not only to closing that knowledge gap, but to making esoteric creatures accessible through art, photography, and social media.

Leucothea sp.

“My own goal is to study underwater life through camera lenses and to boost people’s interest in marine biology,” he says.

Semenov is also leading the Aquatilis Expedition, a three-year-long oceanic research trip to study rare and incredibly fragile, soft-bodied organisms that live 300 feet below the water’s surface. He’s photographed a handful of these creatures, but estimates that 80% of them are undiscovered. The arresting images show jellyfish that look like delicate flora, iridescent Syllidae, and UFO-like Estonian indicans. Catch some of the images in the slide show above.