but for fabian cousteau, it's in his blood. >> you did your first dive at 4. >> i remember. >> i hopebasin of los angeles. >> jacques cousteau says he couldn't explain his love of the sea. he said it made him feel like an angel, being part man, part fish. >> my dad put a tank on my back when i was 7, pushed me overboard. i became a scuba diver. and i've been very, very fascinated by being able to discover part of 70% of the planet, which we all depend upon, as i found out. >> jacques cousteau's grandson is heading down to the depths of the ocean. >> cousteau wants to spend 31 days down under, to break a 50-year-old record set by his grandfather. >> it's a fascinating place. it's in terms of living space, it's 99% of our planet's living space. and there it is at our very thin steps, waiting, begging for us to enjoy and experience it. >> in 1963, academy award winning film maker jacques cousteau coordinated a mission in which six men lived below the ocean's surface for one month. documentary "world without sun" earned him his third academy award. >> we'll never forget when people were a