The IceDragon, a modified Seaglider operated by the Virginia Institute of Marine Science, has explored under the Antarctic ice shelf, and another modified Seaglider, the Deepglider, can plumb the depths down to 6km (20, 000 feet).
There's a sexy high priestess, the dragon fledglings of a would-be queen, and scary creatures encroaching from beyond Westeros's protective wall of ice.