The Navy’s deep sea hunter

HMS Trenchant is one of the Navy’s three Trafalgar-class attack submarines, designed to destroy surface ships and nuclear missile submarines

For this job it carries Tomahawk cruise missiles and Spearfish torpedoes, supported by a range of electronic search and tracking devices

It is propelled by a nuclear reactor which gives it an almost unlimited range and can propel it underwater at more than 30 knots – around 35mph

In November 1990 it snagged the nets of a trawler off Scotland. All four men on the trawler died

In 2013, it completed a 335-day patrol – the longest period away from home for a Royal Navy submarine. During the trip, HMS Trenchant’s chefs cooked 103,350 meals for its crew of 130

It was launched in 1986 and all of the Trafalgar class – there were originally seven – are near the end of their active careers. They are being replaced by the Astute class boats