Grizzly bear chase through a jungle river

Create a hyper-realistic 4K vertical cinematic action scene of a young man running fearfully through a shallow jungle river as a massive roaring grizzly bear chases him closely from behind. He is wearing a sleeveless green jungle vest, rugged cargo shorts, and muddy sneakers. His expression shows intense fear and urgency, mouth open mid-scream. Water splashes dramatically around his legs, and small fish swim beneath the surface. Background shows a dense pine forest with sun rays filtering through the trees and water droplets frozen in air for cinematic intensity. Low-angle perspective. Maintain realistic lighting, sharp focus, and jungle atmosphere.