I was weaving through an underwater forest, russet strands of seaweed billowing around me like mermaids’ hair. As we snorkelled, the water was at times shallow enough that my fins scraped the sand; at others, the kelp-smothered rocks seemed to drop away, leaving the seabed out of reach. A flicker of movement in the corner of my eye had me spinning around to find my guide, Rhionna, pointing to a small, crimson-red sea anemone on a dark rock, its tentacles quivering in the current.