Alex Rivest took a tour around the leading edge of the lava flow on Big Island, Hawaii in December 2010 and his guide decided to demonstrate the viscosity of the molten rock by quickly placing his foot on the surface. The lava was barely displaced by the weight placed upon it, and the main effect of the action was the intense heat that started to burn the guide’s shoe.That’s why Alex advises to never try this by yourself and only ever travel to this area with professional guides. Credit: YouTube/Alex Rivest