CEFR A1-A2. HEADWORDS 750. Dan the scientist works with dolphins. Ludo the dolphin is under the water and can't breathe, so Rosie dives in to help him. But what happens? The sea can be dangerous -there might be sharks! Learners can complete activities whilst reading or after reading – some with supporting activities for the Cambridge Young Learner Test. Picture dictionaries and glossaries help with unknown words along the way. Listen along with downloadable MP3 audio.