Create a serene and enchanting subterranean riverscape set in a lush valley inside a colossal geode cavern, rendered as a Byzantine gold-and-glass mosaic illustration with jewel-like tesserae, bold lead lines, flat perspective, and ornate decorative borders. In the foreground, a woman dressed in a light sweater and jeans sits in a wooden canoe, gently floating on a calm, reflective underground river that mirrors the cavern’s glowing crystal formations. The banks of the river are adorned with vibrantly colored bioluminescent flowers in full bloom—reds, pinks, blues, purples, and yellows—creating a rich tapestry of color across the stone. The river is bordered by charming thatched-roof cottages covered in glowing moss and ivy, giving the scene a quaint and cozy feeling. Luminescent crystal willows and other lush cavern trees overhang the river, their hanging vines softly swaying in the breeze, casting dappled shadows on the water. The scene is bathed in the warm, golden light of a late-afternoon sun filtering through a fissure in the cavern ceiling, enhanced with a psychedelic effect of swirling mosaic colors and slightly distorted perspectives to heighten the sense of peace and idyllic beauty. The entire image is composed in shimmering gold leaf, lapis blue, emerald, and rose glass tesserae, with the psychedelic swirls expressed through rippling mosaic patterns and radiant halos around the canoe and flowers.