From the early days of deepwater exploration when it took a crew of 250 to keep the ship steady enough to collect samples, to the modern-day era of hi-tech minisubs, a century and a half of oceanographic missions is being celebrated. An exhibition at the National Museum of the Royal Navy, Portsmouth has been launched to mark 150 years since HMS Challenger’s remarkable circumnavigation of the world in search of the mysteries of the deep – a mission that led to the discovery of thousands of new species of sea creature and the Mariana Trench. As well as looking back to the 1870s, the exhibition, Worlds Beneath the Waves, looks at some of the exploratory work the modern British navy does. A star exhibit is an autonomous underwater vehicle (AUV), a sort of minisub used to probe the depths. Diana Davis, head of conservation at the museum and the project lead, said: “HMS Challenger was at sea for three and a half years and is widely regarded as being the birth of oceanography. “[The scientists on board] did a lot of stuff, including identifying 4,700 new species unknown to science from the deep ocean. They also collected data on water columns – the different levels of ocean. They found manganese nodules and tiny particles that proved to be from space – cosmic dust – on the sea floor. They found so much it took 50 years to write up the report.” The data is still used today, for example in comparing ocean temperatures and when measuring the thickness of sea creatures’ shells. “Collecting the data was not easy. It took a crew of 250 people to keep the ship steady for them to drop sampling equipment over the side,” said Davis. Exhibits include original samples from the HMS Challenger expedition such as starfish (sea stars) and tube worms that live on the floor of the Pacific Ocean near hydrothermal vents, fissures through which geothermally heated water discharges. The exhibition is not just about the past: it also highlights the work of HMS Protector, the UK navy’s ice patrol ship, which sails the waters of Antarctica. Victoria Ingles, a senior heritage project officer at the museum and the exhibition’s principal curator, said the other key strand was to show how the modern navy carries on the work of Challenger. “Now they can use submarine vehicles to collect the data in a matter of minutes when it used to take days or months to collect.” The exhibition runs for 18 months.