Jenn Caselle and Katie Davis are just back from an expedition to the World's Most Remote island.  Tristan da Cunha is a group of islands in the South Atlantic, and also the name of the main island in that group. The archipelago lies over 2,700 km from South Africa and 3,700 km from the nearest shores of South America. This makes the Tristan archipelago one of the most geographically isolated island groups in the world. The northern group (37°04' S, 12° 18' W) is composed of Tristan da Cunha, Inaccessible and Nightingale islands. Inaccessible and Nightingale lie approximately 30 km to the southwest and south of Tristan da Cunha respectively.  The southernmost and most isolated island, Gough (40°19' S, 9° 57' W), lies 380km to the south southeast. The Tristan group and Gough are volcanic islands formed from the outer slopes of the Mid-Atlantic Ridge and range in age from 200,000 years (Tristan) to around 18 million years (Nightingale).  The Tristan archipelago is a hotspot of endemic biodiversity primarily in terrestrial systems and to a lesser extent in marine systems.  The Tristan Rock Lobster (Jasus tristani) is the most valuable commercial species, and is the target of an MSC-certified sustainable lobster fishery that provides over 80% of the island’s GDP, employs over a quarter of the population at peak times, and provides an essential source of human and cargo transportation via fishing boats travelling to and from South Africa.  The neashore kelp forests (Macrocystis pyrifera, Laminaria pallida) that provide critical habitat for the lobster and other species are of particular interest, especially as the Northern group of islands lies near the limits of temperature tolerance for many kelp species.    Offshore waters are also home to a number of pinnipeds, sharks and cetaceans.  Blue sharks (Prionace glauca) and shortfin mako sharks (Isurus oxyrinchus) are commonly observed in offshore waters while Broadnose sevengill sharks (Notorynchus cepedianus) inhabit the nearshore kelp forests. Large and increasing numbers of sub-Antarctic fur seal Arctocephalus tropicalis breed at the islands and a very small southern elephant seal (Mirounga leonina) population exists at their only known breeding location at Gough Island. Offshore waters also support populations of dusky dolphins Lagenorhynchus obscurus and the rare Shepherd’s beaked whale Tasmacetus shepherdi, and they are also known to be a nursery area for Southern right whales Eubalaena australis.    Both Gough and Inaccessible Islands have been given UNESCO World Heritage Site status for their near-pristine environments and vast wildlife populations.  While all of the Tristan islands ecosystems appear relatively intact and healthy, there are numerous threats, some urgent and some emerging.  On both land and in the water, non-native and invasive species are of primary concern for these isolated islands.  Over the next several years we will be assisting the Tristan islanders formulate regimes of protection for their special islands.