[hristov]

Radio communications for subs are very problematic because water is conductive and more or less shields all radio waves.

AFAIK there is a way to communicate through radio with an underwater sub but involves complex antennas very long radio waves and complex signal processing, etc. There is no way a sub would be able to get a GPS signal under water.

It is possible to have a sub that runs under water most of the time and only occasionally pops up to get its location via GPS, but that would require very complex autopilot software, which the narco trafficers do not have yet.

[tomjen3]

They will get it at some point though - not only are there a lot of programmers who would love to write something as complex as that, but they can afford to pay very, very well.

[ianium]

They basically need a GAVIA[1] system with an extra couple of battery modules and one of the dvl/ins modules to allow for long travel distances with less accumulated error. Build a payload module and screw them all together and you're there. [1]http://www.gavia.is/Products/Gavia-Technology/Payloads/

[mcantelon]

The GPS antenna could be encased in a very small inflatable opaque brown (same color as seeweed/kelp) buoy, attached by a cable to the sub.

[rue]

It is a lot simpler and cheaper to buy or coerce some poor bastard to smuggle for you.