Mini-sub

A Mini-sub, or miniature submarine, is a relatively small submersible, designed for the transport of cargo and personnel and exploration of large bodies of water. Once being the product of war and outfitted for violent engagements, they were redesigned for modern times to serve as deep-sea exploratory equipment, such as those seen in Deus Ex and Deus Ex: Human Revolution.

Unlike the tactical submarines of old and new, mini-subs boast many significant differences: radial arms instead of torpedo tubes and tactical nukes, a bright color scheme such as white or yellow as apposed to the darker blue or black, and generally weighing no more than 150 tons where the largest submarines of the modern fleets can displace up to 48,000 tons.

Deus Ex
The only instance where a mini-sub is seen in Deus Ex is during JC Denton's trip to the Pasadena Ocean Lab. He briefly boards one in order to retrieve some very important schematics from the base on the sea floor, and then again to return to the surface. Walton Simons, one of the games antagonists, also uses one in order to confront JC.

It is one of three vehicles in-game that are animated, as JC is leaving an area, the most common of which is the well known black helicopter. Also, as it is fully automated and its only use is transportation, it may be considered closer to being a bathyscaphe than a mini-sub.

Human Revolution
There are two instances where a mini-sub is seen in Human Revolution. The first is in Panchaea, suspended in a small sub bay, near David Sarif and a few other civilians. It is seen emitting a mist of some type, a possible explanation being that it is warming up and being prepared for departure by the inhabitants of the bay. The second instance involves seeing several docked mini-subs during The Missing Link DLC, when you are taken by elevator down to the Rifleman Bank Station sea-floor labs. If you save Dr. Kavanagh, it is said that she escapes on one, but this is never actually shown or proven.