: It's been there (Scuba diving#Being mobile underwater) since before Anthony Appleyard rejigged the page in December 2004, so I don't suppose we can ask the original author what they meant. Looked at it in comparison with the DPV assertion, I might take a guess that the intention was to say that a diver using a bell can get to an underwater location without having to swim all the down to it (= greater 'mobility'). Similarly, hauling yourself along a shotline with your arms will allow you to move faster than free-swimming. Frankly I find that too much of a stretch of the meaning of the word 'mobility' and I'd be happy to see the "Other equipment to improve mobility includes diving bells and diving shots." sentence deleted.