The hardware platform of the Seamonkey is based on the now-classic Cornell's twin-hull-on-aluminum-frame concept. The central frame provides easy access for mounting sensors and any other payload. The larger top hull houses the vehicle electronics, while the bottom hull contains the vehicle's batteries and motor controllers. The combination of relatively high buoyancy in the top hull and greater weight in the bottom hull gives the vehicle an excellent static stability on the roll axes.

Two thrusters on the sides of the vehicle allow it to move forward and backward as well as turn left and right (also known as yaw). Two more thrusters mounted at the front and back of the vehicle allow it to surface, dive, and pitch. Together those motions: forward/back, yaw, surface/dive, and pitch provide 4 degrees of freedom. the other two degrees of freedom the vehicle could have are lateral motions left and right, and roll. Our design does not allow for lateral motion. Instead we rely on precise control to combine turning and forward motion to make lateral movements. The Seamonkey doesn't have active roll control because roll is compensated for passively.

Seacon underwater connectors are used between the hulls, thrusters, and sensors to route all the power and signals between devices.