Activating this trainer:
Press F1 at main menu.
Listen for 'Trainer Activated'.
Press desired hotkey. All hotkeys can be changed on the trainer.
NumPad1: Infinite Health
NumPad2: Infinite Food
NumPad3: Infinite Water
NumPad4: Infinite Oxygen
NumPad5: Easy Crafting
NumPad6: Super Swimming Speed
While active you can things for free.
Super Swimming Speed:
While active you can hold down while swimming to gain super swimming speed.
Press CTRL+H at any time to temporarily mute all (except this) hotkeys.
Press again to unmute. You can change this hotkey in the trainer settings.
You can also mute specific hotkeys by changing the hotkey you want to mute to 'NONE'.
Unlock more trainer options including updates from here - Subnautica Trainer