The marine environment houses complex types of ecosystems that provide vital services and habitat to aquatic life. Areas of the seafloor where rocky outcrops are present, such as reefs and gravel beds, are some of the rarest marine habitats. Also known as ‘hard substrate habitats’ these ecosystems are under increasing pressure from fishing, eutrophication, climate change, and coastal management. Though hard substrates are protected in the European Union, we are unable to manage them effectively because maps describing their location and dimensions are inaccurate. In a review paper, Dr Svenja Papenmeier [Sven-yah Pah-pan-my-er] of Germany’s Leibniz Institute for Baltic Sea Research Warnemünde summarises existing rules for mapping substrate habitats, and describes new and potentially ground-breaking mapping techniques.