One our recent Tesla Model 3 test drive we crossed from Denmark to Sweden on a 100% battery electric ferry. The 4 kilometre crossing between Helsingborg in Sweden and Helsingřr 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. More info: https://www.forseaferries.com/