"The unmanned vehicle is remotely operated by pilots aboard a surface ship via a lightweight tether. Its thin, fibre-optic tether to the research vessel Kilo Moana allows the submersible to make deep dives and be highly manoeuvrable. Nereus can also be switched into a free-swimming, autonomous vehicle. ... The Challenger Deep... is the deepest abyss on Earth at 11,000m-deep, more than 2km (1.2 miles) deeper than Mount Everest is high. At that depth, pressures reach 1,100 times those at the surface."
Hmmmm lets see 11,000m that's 11km. Yup 11 > 2 ... good job!
For anyone in a nation that hasn't switched to the metric system and still care how long the king's foot is, that's >6miles.
Orignal source seems to be the BBC.
As Homer would say "SMRT".