Regulator hoses! They're being pressurised, de pressurised, put in salt water, folded into your gear bags, pulled about... they really have a hard time!
While we have to accept that you need to replace your hoses (most manufacturers recommend every 5 years by the way- they are a consumable) you can help to reduce the wear and tear by fitting hose protectors. These rubber protectors slide over the hose and fit onto the 1st stage end. This helps reduce the strain of bending and pulling on those essential hoses.
Pro tip - if you have hose protectors on your regs make sure you pull them back while rinsing to minimise corrosion on the metal fittings!