Activating this trainer:

Press F1 at main menu.

Listen for 'Trainer Activated'.

Press desired hotkey. All hotkeys can be changed on the trainer.

Trainer Options:

NumPad1: Invincible
NumPad2: Infinite Food
NumPad3: Infinite Water
NumPad4: Infinite Oxygen
NumPad5: Easy Crafting
NumPad6: Super Swimming Speed
NumPad7: Super Damage
NumPad8: Fast Build
NumPad9: Fast Scan
NumPad0: Fast Hatch
NumPad/: Fast Grow
NumPad*: Unlock Doors
NumPad-: Unlock Developer Menu
NumPad+: Infinite Power
NumPad.: Infinite Exosuit Health
Page UP: Infinite Seamoth Health
Page Down: Infinite Cyclops Health
Insert: Super Speed 4
Home: Infinite Fire Extinguisher

Notes:

Invincible: While active nothing will hurt you.

Easy Crafting: While active you can things for free.

Super Swimming Speed: While active you can hold down while swimming to gain super swimming speed.

Super Damage: While active ANYTHING except yourself will take super damage on hit.

Developer Menu: While ingame press ESC, then activate this cheat. A new menu button appears which gives you access to the developer menu.

Super Speed: This speeds up the overall game.