Gibraltar Rock rises 411 m (just six meters short of NYC’s WTC prior to 2001) over the strait; but just two miles south depth is twice that figure. Who knows what is under water? surely lost ships, scores of submarine sensors, and who knows what else. Depth is quite enormous when compared to other known straits: the English channel is just 174 m deep at most, so there is little wonder in  the fact that all the talk about a fixed rail/car link between Spain and Morroco have produced little outuput until now.