Yes, we use these in ocean bottom and subsurface buoys. However only for audio and seismic activity do we need this kind of accuracy. The cost is high, they

Yes, we use these in ocean bottom and subsurface buoys. However only for audio and seismic activity do we need this kind of accuracy. The cost is high, they don't always work perfect, and they consume a fair amount of power for long deployments. Overall we try to avoid them if possible.