Scuba tanks
Scuba tanks are heavy. average Scuba tank would weight around 20kg. But regarding Sharm el Sheik diving business, it is much cheaper to rent them locally for average diver.
Technical divers might want to bring their specialized equipment with them. Also deep divers use pure O2 for breathing in very shallow depths after very deep dives to get rid of excessive nitrogen dissolved in body.
But, all tanks that you take with you aboard, are required to be with open valves. Empty it means.
So, if rules were followed then scuba tanks pose absolutely no risk.