Marine acoustician Tim Lewis listens to a large pod of dolphins captured by a hydrophone on the Arctic Sunrise in the Indian Ocean.

The Saya de Malha Bank is part of the Mascarene Plateau and located between Mauritius and Seychelles in the Indian Ocean. It is the largest seagrass meadow in the world and one of the biggest carbon sinks in the high seas. A team aboard the Greenpeace ship, Arctic Sunrise are on an expedition to the bank to contribute to a better understanding of the wildlife and diversity of the region and make the case for this area to be protected.