May 7th, 2009 
If successful, Nereus will be the first autonomous vehicle to visit the 11,000m (36,089ft) Challenger Deep in the Pacific Ocean. Only two other vehicles have ever visited the spot before, both of them human operated. The $5m submarine will make the attempt in late May or early June after a series of increasingly deep dives.
Of course the really cool thing about Nereus is that is transformer. Depending on the mission it can switch between an autonomous underwater vehicle (unteathered to the surface) to a remote operated vehicle (tethered) depending on the mission.
Broadcast Spawn!
[...] PhysOrg… Using the 11,000 meter-rated Nereus hybrid remotely operated vehicle (HROV) as a test platform, engineers at WHOI recently demonstrated a new communications and control [...]
[...] To the working combinations list, I would add Nereus. The deep-sea transformer that tranforms from a remotely to autonomous underwater vehicle. [...]