Offshore airborne wind turbine systems with an aerial vehicle connected to an undersea anchor via a tether are disclosed. A floating landing platform may be coupled to the tether and be dragged along the surface of the water along with the tether. The landing platform may be designed such that the tether can freely pass through the platform, allowing the aerial vehicle to ascend, descend, move laterally, and in crosswind flight, without creating a significant tension load on landing platform. The landing platform may also include a tether drive mechanism that can actively move the tether through the platform, thus changing the platform's location along the length of the tether.