beautiful this section ... I'm only going for so many years, since my first training.
Just dive into the water means to me and just do all the dive alone. gas planning, dive profile and equipment not only for me and for a possible rescue. Always avoid crossing other divers.
Usually, when I go alone, there is always someone on the ground for any help if I go beyond the agreed time.
Only go down from 5 years with the configuration sidemount I believe the best security.
Here in Italy I dive into the lake with very cold water (6 °) and significant depth. Often Trimix and nitrox for deco. Even at sea I go alone, but always with the support boat.
I bring with me a pocket with necessary tools to fix hoses and dispensers, pliers, a knife, two computers on the gauge, depth gauge (Magic 300), tables, 2 Spool ....
The Solo Dive is a lifestyle choice. IMHO.