The typical wave tank is a box filled with liquid, usually water, leaving open or air-filled space on top.
[1] A similar device is the ripple tank, which is flat and shallow and used for observing patterns of surface waves from above.
Also (3D) constructions providing little blockage to the flow may be tested, e.g. measuring wave forces on vertical cylinders with a diameter much less than the flume width.
[4] Often, the side walls contain glass windows, or are completely made of glass, allowing for a clear visual observation of the experiment, and the easy deployment of optical instruments (e.g. by Laser Doppler velocimetry or particle image velocimetry).
In 2014, the first circular, combined current and wave test basin, FloWaveTT, was commissioned in The University of Edinburgh.