Airships seem to be experiencing something of a back-to-the-future moment. TheZeppelinsand other massiveairships of the 1920s and 1930s are infamous for their dramatic disasters. The Hindenburg disaster of 1937 made it seem like the lid had closed onairshipsfor good. But not so fast. Airships never entirely disappeared and have been used for tourist flights, intelligence gathering, and other functions. If hurdles can be overcome, they could be transformative in transporting heavy and bulky cargo worldwide. Here are five airships under development today (plenty more airships are being made, such as the Solar Airship One).