I interviewed a guy who worked for Schlumberger (provide a lot of tech to oil and gas industries)... Anyway, he was describing something to me in a thick accent and it finally dawned on me what he was saying... Shocked, I leaned forward and said: "You were transmitting data via mud?" and he said yes.
See, when you're drilling very deep.... radio waves can't get down to the drill head... but you can put a computer down there to detect what kind of material you are drilling in... You also have to pump this mud stuff down and out to get the material the drill breaks free out of the hole.... their solution was to vibrate a pattern into the mud and then have another computer that optically read the pattern from the mud at the surface! He then proceeded to tell me the bitrate he achieved on this "network".