How to bind and configure deepfly:
It is 
highly recommended to read the article below thoroughly, you may learn a bunch of useful things.
URL:
https://wiki.ddnet.org/wiki/Binds#Deepfly
If you prefer to not read the article:
Move the attached text file to your config directory, and then type: 
exec deepfly.txt into the ingame console (F1).
To toggle deepfly on/off, press "C" on your keyboard.