Deep inside Switzerland's Gotthard mountain, researchers are creating earthquakes on purpose. By pumping thousands of tons of water into the rock, they've already triggered more than 3,000 microquakes. Hundreds of sensors installed directly on active fault lines show how earthquakes start and spread. Then we head underground to uncover the surprising story of salt: how it forms, how it's mined and why salty wastewater is damaging Germany's Werra River. Sea lettuce is growing beneath a spa in eastern Germany. Fed by natural brine instead of precious freshwater, the algae could help shape the future of sustainable food and farming. And finally, we look at a growing concern: many people in Germany consume too much salt but still don't get enough iodine. Iodine deficiency can affect the thyroid gland, pregnancy and child development.