One day, a scuba diver was out diving out in the ocean about 10 metres down.
Looking around him, he noticed a man swimming at the same depth, but without any scuba gear on, not even a mask or fins.
To show the man how amazing it was to be able to scuba dive, the diver decided to go down another 10 metres, looked around, and lo and behold, there was the same man, still swimming away.
“I can’t believe it”, the scuba diver thought, “I bet he can’t go down any deeper”, so he dives down another 10 metres and the man is still there, swimming away!
Totally amazed, the scuba diver pulls out a chalkboard and writes: “How the heck are you able to go so deep and stay under so long without any equipment?”
The man grabs the chalkboard and writes, “I’m drowning you moron!”
Image used under a Collective Commons License from https://pxhere.com/en/photo/1344539