At TNO The Hague a large (8x10x8m) anechoic basin, ideally suited for a large variety of underwater measurements, is available
This large anechoic basin at the Dutch TNO research centre can be made available for your measurements. They can do the measurements for you or you can rent the basin. The basin is primarily designed for acoustic measurements, such as calibration of hydrophone arrays and streamers, acoustic holography measurements, single hydrophone and transducer calibrations, measurements of echo strength of submerged objects, etc.
Besides the acoustic measurements, the basin is also perfectly suitable for other types of underwater measurements. in the recent past it was used for calibration of radio-active oil well measurement equipment, for the testing of underwater radar applications, for measurements on sediment types, for testing and calibration of fishery equipment, etc.
Take a deep dive and read more at the TNO website