Approximately 70% of the Earth is covered in marine water, and much of this vast area is considered the “deep sea.” Despite the size and importance of this extensive part of the “Blue Planet,” most of the deep seafloor remains unexplored, and we are only beginning to unveil the mysteries of deep-sea inhabitants. The deep seafloor is comprised of a diverse array of habitats, including methane seeps. Methane seeps are places where methane emerges from seafloor sediments without an appreciable temperature rise, and are among the most recently discovered marine habitats. Methane seeps are widespread, and, in addition to their potential as energy resources and capacity to cause tsunamis, have linkages to climate change and are home to unique creatures. Methane seeps and other deep-sea habitats will be examined with discussions that show the use of the latest technologies, including manned submersibles, such as Alvin (most famous for its role in the discovery of the Titanic and hydrothermal vents) and remotely operated vehicles, such as Jason. Images and discussions will also be included that focus on the strange and unique seafloor habitats and ecosystems of methane seeps off Alaska, California, and Costa Rica (from 500 m to 4450 m).