Hercules weighs 5,200 lbs. in air. So, it needs some help with floating, or buoyancy with all that weight. It has a yellow, thick layer of syntactic foam on top to assist with buoyancy. The foam is made of small, hollow glass balls and a resin of epoxy that can withstand the heavy pressures of up to 4, 000 meters of water pushing down on it. It is considered as a positively buoyant vehicle which means that if it gets separated from Argus (i.e. cable breaks), then it will float to the surface instead of sinking to the bottom.