Big Blue sets out on an expedition to discover the secrets of the blue whale, and reveal its unknown calving and breeding grounds. National Geographic has supported the research of the worlds top blue whale scientist for years. Now, by working with them, we go on a mission around the globe. We dive deep under the surface with blue whales to discover what they do at depth. We use satellite tags to reveal their mammoth migrations. We identify individual whales to understand populations. DNA analysis reveals gender related behavioral differences. We explore the sea floor and water currents to uncover blue whale feeding strategies. Hydro acoustic microphones reveal whale song and whole dialects in blue whale communication. Ultimately we follow the California population of blue whales to a remote area of open ocean off Costa Rica . If we and our scientists are right, we will reveal the secret calving and breeding grounds of blue whales.