A photorealistic depiction of a bioluminescent underwater city, built within a massive, hollowed-out ancient tree trunk, deep in the Amazon rainforest. The city's inhabitants, a tribe of indigenous people, have adapted to living underwater, their skin glowing with the same bioluminescence as the city's flora and fauna. Capture the interplay of light and shadow as the bioluminescent glow illuminates the murky depths of the river.