We join Cal on her paddleboard as she sets off from Glasgow city centre, following the River Clyde out to sea. Ahead of her lie vast ocean crossings as she island-hops past whirlpools to Arran, Mull to Skye. We get our first glimpse into Scotland's surprising underwater world, to experience what is often out of sight and out of mind, and hear about some powerful community projects to protect it.

We continue up the Wild West coast, where the sea suddenly feels very different. Cal experiences the wildlife encounter of a lifetime when Scotland's apex predator joins her in the water. We meet fishers and a group of very determined children. The indomitable Cape Wrath and North coast test Cal like never before, and just when things start to look up, she makes a heart-breaking discovery.

Reeling from her discovery, Cal delves into the topic of marine mammal entanglement. Just as spirits start to lift, she encounters more wildlife in distress, and her veterinary training comes to the rescue. We experience the beauty of the East coast and its thousands of nesting seabirds, get in the water with fellow ocean lovers and dive into just how powerful connecting to the ocean can be.