The depths and ages for kids to learn how to scuba dive with PADI, BSAC, NAUI and SSI.
A drysuit should be a snug fit with room for insulation undergarments under it so you can still move freely when you’re wearing it. You should not experience too much restriction on movement with layering under the drysuit, as this would indicate the drysuit is too tight. But if there is no resistance to movement, the drysuit may not be tight enough.
It is important not to dive with an excessively tight neck seal, as a very tight neck seal will restrict blood flow to your brain, which in a worst case scenario can lead to brain damage and be dangerous. A very tight neck seal will also be uncomfortable and will be difficult to get over your head.
You can set most drysuit exhaust valves to vent air automatically while underwater, but to do so the air in your drysuit needs to migrate to where the exhaust valve is located on the suit. You can adjust the valve and how much air is released, but it’s best to have the valve set to fully open.
You could wear a wetsuit under a drysuit, but it’s not the best way to keep you warm. So you should wear an under-suit that’s designed for wearing under a drysuit, which is designed to keep you warm instead.
The scuba diving basics include mastering your buoyancy control and mastering your air consumption to extend your dive time and have fun diving.