Blue World

The "Blue Hole" is a portal that leads back to the prehistoric age. In light of this astonishing discovery, the United Kingdom and the United States dispatched a joint team to the Jurassic world 145 million years ago for a full-scale investigation. But a sudden disturbance cut off their communication with the modern world. Only a few people and their equipment are left. A survival adventure in a terrifying world where everything is unknown and dinosaurs roam free has begun!
(Source: Kodansha, translated)