Seastar platforms are basically smaller tension leg platforms. The Seastar platform consists of a floating rig, as for the semisubmersible drilling rigs. A lower hull is ballasted with water when drilling, which increases the stability of the platform movement from environmental loads. In addition to this semisubmersible rig type of features, Seastar platforms also incorporate the tension leg system found in larger platforms. The tension legs are long and hollow and extend from the seafloor to the floating seastar platform. These legs are kept under constant tension, and prevent any vertical movement of the platform. Their flexibility does however allow for horizontal motion, which allows the platform to withstand the loads of the sea and wind, without breaking the tension legs off. Seastar platforms are typically used for smaller deep-water reservoirs, were it is not economical or practical to develop a larger platform. They can operate in water depths of up to 1000 meters.