No Way Up; Building the Elite Athlete; Scientific American Presents; by Michael Menduno; 6 Page(s)

George Irvine and fellow explorers Jarrod Jablonski and Brent Scarabin are five kilometers from the mouth of Florida's Wakulla Springs. Trailing behind their torpedo-shaped underwater scooters, they barrel through the water-filled cave at a depth equivalent to a structure excavated 30 stories down into the earth. The watery darkness presses in around them, swallowing the beams of their 100-watt arc lamps. The recesses of the submerged limestone tunnel have not been illuminated in the millions of years since the sedimentary rock accreted from the remains of dead sea creatures.

After descending for 30 meters through the clear waters of a lake to the cave entrance, the daredevil crew has motored in formation for more than two and a half hours. The gaping underwater passageway-big enough to accommodate a taxiing 747-shows no signs of narrowing as the men press on with their mission of finding the elusive source of the waters that well up to the surface, where bald cypress trees line the shore and alligators make their home.