One of Britain's seven Trafalgar class nuclear subs was slightly damaged when it bumped into a small iceberg while submerged, on May 25th. The HMS Tireless was returning from Arctic waters where it was apparently training. The sub must return to its base for a full assessment of the damage. The hull was not breached, but there is at least a dent. Recently, another Trafalgar class sub had an expensive encounter with offshore rocks. HMS Trafalgar underwent $8 million in repairs when it ran aground off the Isle of Skye.