Sorry, you can’t (to answer the question in the title) but you can walk on the next best thing – Oobleck. Oobleck is a non-newtonian fluid made up of a mixture of corn starch and water. I have played with a small quantity of it in a bowl but have never been able to walk across it 8,000 liters of it!
httpv://www.youtube.com/watch?v=D-wxnID2q4A
If you feel inspired, a recipe can be found here.