Life in inaccessible places - including in caves sealed off from the Sun and around deep-sea vents - is the subject of this week's Naked Scientists. In these intriguing environments, bacteria replace plants as the primary producers, extracting energy from the minerals around them to sustain a whole ecosystem. We also hear about the bone-eating worms that make a meal of whale carcasses that fall to the seafloor, an engineering trick for separating mined-metals from mud and, in the news, why the world's waves are getting bigger, how sperm can be grown in a dish and a gene that drives melanoma. Plus, the answer to the question where on Earth would you weigh the most...?