An enchanting underwater cave illuminated by a soft blue-green glow, with walls covered in ancient, glowing carvings of mystical symbols. Lucy, an 8-year-old girl with short golden ponytail hair and bright, curious blue eyes, swims cautiously through the crystal-clear water. She wears a damp white shirt and green overalls, her small hands carefully holding a shimmering crystal shard she found in the depths. Her expression is a mix of determination and wonder as she explores the magical surroundings.