Aerogels are the world's lightest (least dense) solids. They are also excellent thermal insulators and have been used in numerous Mars missions and the Stardust comet particle-return mission. The focus of this video is silica aerogels, though graphene aerogels are now technically the lightest.
The 4 kilometre crossing between Helsingborg in Sweden and Helsingør in Denmark doesn't seem that far, but this ferry is crossing up to 46 times a day, and charging for a few minutes each side. The route handles more than 7 million passengers and almost 2 million vehicles each year with crossings every 15 minutes.
