Abstract: An underwater system including at least one input device that is in sensory communication with water and generates input signals. The system further includes at least one optical transmitter and at least one optical receiver that allow omni-directional transmission and reception through water of optical signals representing the input signals, and allow data rates greater than 1 Mbps.

Abstract: An underwater system including at least one input device that is in sensory communication with water and generates input signals. The system further includes at least one optical transmitter and at least one optical receiver that allow omni-directional transmission and reception through water of optical signals representing the input signals, and allow data rates greater than 1 Mbps.

Abstract: A passive exercise apparatus includes an interface member for coupling to a user's limb. An arm member is coupled to the interface member by a wrist joint. The wrist joint has rotational motion about three axes. A first link is coupled to the arm member by a sliding joint. The sliding joint allows translational motion of the arm member relative to the first link. A second link is rotatably coupled to the first link by a first rotary joint. A third link is rotatably coupled to the second link by a second rotary joint. A first brake is coupled to the first rotary joint for resisting movement of the first rotary joint. A second brake is coupled to the second rotary joint for resisting movement of the second rotary joint. A third brake is coupled to the arm member for resisting movement of the arm member. The user is capable of interfacing with the apparatus to exercise a six degree of freedom motion.