Nearly all diving gear is really heavy as sinking is desirable so weight is not "designed out". Some of the "gear" will likely be lead weights.
Deep (nitrox) diving with gas management and hyperbaric medical support is (for me) closer to Vacc suit (i.e. the suit is the dive vehicle and what's outside of it will more or less immediately kill you). In RL it really isn't the sort of thing you can just "have a go at" - because mismanaging your suit will kill you too!
Of course Traveller PCs are heroic adventurous types and may well be up to the challenge!

