The first part of the article provides an overview of both single-axis and multi-axis wave energy converter (WEC) technology, with a particular focus on present and past prototype devices. The second part of the article considers a multi-axis concept device that has been developed and tank tested at Lancaster University by successive Master of Engineering project teams. TALOS is a point absorber-style device, built as a 1/100th scale representation, with a solid outer hull containing all the moving parts inside. The internal power take-off system is made up of an inertial mass with hydraulic cylinders, which attach it to the hull. The mass makes up a significant proportion of the mass of the device, hence it moves around as the hull is pushed by various wave motions i.e. an inertial mass power take-off approach. The latest design has proven to be successful in wave tank testing, in that the power take-off system yields a smooth output in response to time varying inputs from the waves. An analytical model was developed to combine data from the hull model and hydraulic rig, yielding a predicted power output of up to 3.2 kW.