They’re microscopic, mysterious, and mighty. In this episode of Saltwater Stories, we dive deep into the hidden world of phytoplankton, the tiny ocean drifters that generate half the oxygen we breathe, fuel marine food webs, and shape our planet’s climate. From glass-shelled diatoms and glowing dinoflagellates to ancient cyanobacteria and chalk-armored coccolithophores, discover how these invisible powerhouses build ecosystems, combat climate change, and even inspire biofuel and pharmaceutical innovations. But all is not calm beneath the waves. Harmful algal blooms and shifting ocean conditions threaten this delicate balance. Join us as we uncover the wonder, complexity, and critical importance of the ocean’s tiniest giants.