From our planet's underwater caves to its ancient soils, there are entire worlds right beneath our feet. On this week's show, we explore the subterranean forces that shape our lives above the ground.

Underneath the surface, there lies a vast network of natural and manmade waterways. Cave diver Jill Heinerth shares her adventures through our planet's plumbing and the ways it secretly connects us.

We compost plants and livestock, so why not humans? Katrina Spade says that if you want to help the planet one last time, consider composting your body.

 Earth's soil can store vast amounts of carbon. Biogeochemist Asmeret Asefaw Berhe says soil could be a powerful tool for fighting climate change - if only we stopped treating it like dirt.

The largest predator in history was bigger than a T. Rex and longer than a schoolbus. And it swam. Paleontologist Nizar Ibrahim shares his quest to uncover the Spinosaurus.