NASA is planning to build a submarine that will one day be used to explore Saturn's moon Titan, largest and deepest hydrocarbon ocean "Kraken Mare". The project is just in the conceptional level with the mission inauguration in 2038, at the earliest.
Although Titan is a moon, Saturn’s natural satellite Titan is curiously planet-like. More particularly, it has outstanding relationships with Earth such as clouds and a dense atmosphere. It does, however, have many oceans of liquid methane instead of water, as its temperature is far too icy for liquid water to exist. This would make is most painful for much of life on Earth. Still, researchers have reasons to consider that life could appear under these strict circumstances since its dense atmosphere has much methane and other organic compounds, signs revealing of life from Human being perspective.
According to NASA, methane would have been permanently demolished by sunlight after tens of millions of years. On Earth, methane is replaced by the metabolism of living organisms. What replaces Titan’s methane and keeping it in large quantity is one of the mysteries that lead researchers to consider there might be, or may have been, organisms blamable for Titan’s atmospheric content. To get to the end of the mystery, NASA is boarding on what BBC calls the "most revolutionary mission ever tried." They are planning to build a submarine that would one day explore the terribly named Kraken Mare, Titan’s largest and deepest ocean, a hydrocarbon body bigger than the Caspian Sea.
Kraken Mare. NASA
A brief explanation by NASA says that the submarine will be unmanned yet accomplished: "Titan Submarine, or Titan Sub for short, will be entirely self-directed, highly skillful science craft that will permit a complete investigation of what exists underneath the waves in another world."
It will also help as a follow through to the previous surface mission Titan Mare Explorer (TiME) and "will explore a full scale of oceanographic phenomena. "While this is electrifying, it will take time before the conceptual Titan Submarine is realized, much less launched to Titan. Recreations estimate that its latest possible arrival to the planet-like moon is 2038, when alliances between Earth, Saturn and Titan are promising.