First we have to find a blue whale, which can be very difficult because these animals range across vast swaths of the open ocean. By combining many years of field experience and some luck, we position a small, rigid-hulled, inflatable boat on the whale's left side, we then have to deploy the tag using a six-meter (20-foot) long carbon-fiber pole. As the whale surfaces to breathe, we tag the whale in a location that we think is closest to the heart: just behind the whale's left flipper.