The bathyscaphe was a type of a manoeuvrable free diving submersible. It appears to be powered by two Vickers electric fans, which can pivot 180 degrees, allowing for a large field of motion. It features two robotic arms at the bow of the vessel, that can be used to cut or manipulate items in the surrounding environment. They are stored inside the main lower bay of the Upholder-class submarines main usage is that of repairs and maintenance at sea.
After the HMS Gartside is attacked by a Liopleurodon, the submarine's sonar array becomes tangled around the propeller, and it becomes marooned in the Jurassic period. While Connor Temple stayed aboard the submarine, Abby Maitland and Matt Anderson boarded the bathyscaphe to attempt to make repairs on the vessel's exterior. They exited the lower bay, and proceeded to the stern of the submarine, and found that the cables leading to the sonar array had become tangled around the propeller shaft. While Matt steered the bathyscaphe and kept it steady, Abby used one of the robotic arms to cut the cables. Just after she cut the last of the cables, a Liopleurodon attacked the small submersible. After Matt realised that it was not one, but an entire pod of Liopleurodon, he ordered Abby to cut the power to the bathyscaphe. She did so, and thinking that it was a lifeless organism, the Liopleurodon refrained from attacking it. Abby then turned on the power, and the two of them made their escape into the relative safety of the hull of the HMS Gartside.
Real bathyscaphes are much larger and much less quick than the one portrayed in Primeval. They are designed with extremely cramped quarters with very thick walls, so as to be resistant to extreme temperatures and pressures of the deep ocean. This one was heavily based on the new-age submersible, Deep Flight II. However, the robotics systems were much more similar to those of the Alvin, another deep-water vessel.