A 300 foot dive with an air hose as shown is not possible due to the pressures, 10 atmospheres;however, 50-60 foot could be done. Writers generally fail at science and tech.
During the dive scene, all of the non-water proof electrical equipment has been underwater for duration, then magically is able to run. It also doesn't kill the main character. The laws of physics do not apply in the Silo.