After starting with a swim in a freezing loch, the bike course for this stunning event takes in the grueling roads of the Scottish Highlands before the monumental run up and down Britain’s highest mountain, Ben Nevis. With this year’s race decided in the final stages, as the leaders struggle with injury, Rob Walker presents coverage of what is very probably the toughest triathlon in the world over the half-iron distance – only Bravehearts need apply for this.