Recreational scuba instructor since 2008. People think it's extreme as fuck, and badass and all. It's honestly really Zen. You take long, slow, deep breaths; often wearing a wetsuit or drysuit which reduces the sensory input on the body; you can't talk to anyone else (unless you have a full face mask and comms system/are fluent in sign language); mechanics of sound through water mean that everything is muffled and sounds like it's above you; you're (ideally) neutrally buoyant, so you're drifting through your surroundings.

It made a hell of a lot of sense why this was my career choice when I got an autism diagnosis in 2019.