people died. >> reporter: the conditions are so dangerous to man, dr. ballard and his team are relying on hercules, a 5-,000 pound submersible to be their eyes and ears inside the volcano. this is the season's final dive. >> now we are reaching the top of the volcano. >> we're in it. we're inside the crater. you can see it is surrounded by -- we're inside. >> oh, wow. >> reporter: on its journey, hercules is doing more than taking breathtaking pictures. it is collecting samples, making maps and reaching right into the volcano's plume. after hours of searching, a startling discovery, life. >> oh, that's a perfect shot right there. >> what could this potentially mean? >> well, in this particular case, it means that places that we thought there was little life existing on our planet we just opened another area where life seems to be thriving. >> reporter: after a six-hour