Line a 9x13 pan, both bottom and sides, with parchment paper and set aside until ready to use
Combine the sugar, golden syrup, water and salt in a large sauce pan, the mixture will expand a lot so use a pan or pot with plenty of extra space.
Gently stir the mixture to get all of the sugar wet and then heat on medium heat, swirling the pot to ensure all of the sugar dissolves.
When the mixture begins to boil, clip the candy thermometer to the side of the pan.
Heat the mixture to 300 degrees Fahrenheit, swirling the pan to ensure the mixture is heating evenly. Have a whisk ready for the next step.
Once the mixture reaches 300 degrees Fahrenheit, remove from heat and whisk in the baking soda, taking care to ensure the entire mixture gets mixed with the baking soda.
Once the mixture has fully expanded, pour into the prepared 9x13 pan and leave to set at room temperature for at least one hour.
Once the mixture has set, remove from the pan and using a knife, break the mixture into pieces.
The honeycomb can be eaten as is and can be stored for up to a week in an airtight contrainer. Use wax paper when storing the pieces since they get stickier the more they're exposed to air.
If desired, the honeycomb pieces can be dipped or coated in chocolate.