Um, 'heavy water' means water with a highly-enriched count of deuterium/tritium, if I recall correctly. I'd think that's at a level a bit too low to allow someone to walk on it. And I'm having trouble picturing the existence of a chemical that could increase surface tension that much without causing harm to his feet...remember, he did take his shoes off for a short distance.

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If you have sufficiently callused feet, it is even possible to walk on acid. So the chemical he was using prob won't hurt his feet?