Sitä saavat aikaan mm. sota-alukset etsiessään sukellusveneitä - kaikuluotaamalla samalla taajuudella kuin delfiinit. ###>And while it looks very obvious to us, standing on the beach, that there's a big beach there, if you were to put yourself 50 metres offshore with a face mask on, swimming around, and not look above the water and get a clear picture, it's very easy to get disorientated.