Mining the seafloor and space have been discussed for decades, but the anticipated increase in demand for critical minerals has renewed interest in these unexploited frontiers. Courtesy of Patricia Alexandre via Pixabay

For years, many viewed companies and investors that set their sights on opening up new mining frontiers in the deep seas and space with skepticism. Mining the oceans was seen as unviable, while mining the Moon or asteroids was considered to be something from science fiction.