> Why can't satellites map the topology using something like RADAR If you were close enough, say in a plane, you could do something to cause a soundwave to pro

> Why can't satellites map the topology using something like RADAR If you were close enough, say in a plane, you could do something to cause a soundwave to propagate through the water. Say you fire a femtosecond laser pulse or blast it with an ultrasonic pulse. You could then, probably, use a second laser to pick up the reflections as disturbances on the surface. Otherwise you're probably stuck, since RF doesn't propagate well through a conductive fluid. Submarines can communicate somewhat using very, very low frequencies of electromagnetic energy, but the problem with that is the resolution at those wavelengths would be very, very poor. The best bet at this point in time is probably to just make a bio-mimicing, underwater drone and map under the surface. If you were really clever, you'd just hook some electrodes into a whale's brain and make it carry your mapping payload, using whale sounds to map the ocean floor. Not very nice thing to do to a living creature, but we've done very bad things in the name of national security before.