Question: Speleonaut, is the submersible used by the cave diver Jochen Hasenmayer, after the 1989 decompression accident that left his legs paralyzed, Hasenmayer designed the "Speleonaut" with his friend Konrad Gehringer in order to continue exploring the Blauhöhle cave system, which begins at the base of which spring that serves as the source of the river Blau in the karst landscape on the Swabian Jura's southern edge, in Southern Germany?

Context paragraphs:
Sirgenstein Cave: The small Sirgenstein Cave, German: "Sirgensteinhöhle" is situated 565 m above sea level inside the 20 m high "Sirgenstein", a limestone rock.  The cave sits 35 m above the Ach River valley bottom in the central Swabian Jura, southern Germany.  Archaeologist R. R. Schmidt excavated the site in 1906 during which he identified indices of prehistoric human presence.  He recorded the complete stratigraphic sequence of Palaeolithic and Neolithic origin.  In his 1910 analysis Schmidt inspired future archaeologists with his pioneering concept of including the excavation site within its geographic region, contextualizing it within a wide scientific spectrum and demonstrated valuable results as he correlated the Sirgenstein layer structure to those of prehistoric sites in France.

Geisenklösterle: Geisenklösterle (German: 'Geißenklösterle' ) is an archaeological site of significance for the central European Upper Paleolithic, located near the town of Blaubeuren in the Swabian Jura in Baden-Württemberg, southern Germany.  First explored in 1963, the cave contains traces of early prehistoric art from between 43,000 and 30,000 years ago.  In 2017 the site became part of the UNESCO World Heritage Site Caves and Ice Age Art in the Swabian Jura.

Blau (Danube): The Blau (] ) is a 15 km long river in Baden-Württemberg, southern Germany, and a left tributary of the Danube.  The source of the Blau is the karst spring of "Blautopf", in the town Blaubeuren, in the Swabian Jura.  It flows east through Blaustein to the city of Ulm, where it empties into the Danube.

Jochen Hasenmayer: Jochen Hasenmayer (born 28 October 1941 in Pforzheim, Germany) is a German speleologist and cave diver from Birkenfeld in Baden-Württemberg, whose spectacular dives have frequently made headlines.

Hohle Fels: The Hohle Fels (] ) (also Hohlefels, Hohler Fels, German for "hollow rock") is a cave in the Swabian Jura of Germany that has yielded a number of important archaeological finds dating to the Upper Paleolithic.  Artifacts found in the cave represent some of the earliest examples of prehistoric art and musical instruments ever discovered.  The cave is just outside the town of Schelklingen in the state of Baden-Württemberg, near Ulm.  In 2017 the site became part of the UNESCO World Heritage Site "Caves and Ice Age Art in the Swabian Jura".

Blautopf: The Blautopf (German for "Blue Pot"; "blau" means "blue", "Topf" means "pot") is a spring that serves as the source of the river Blau in the karst landscape on the Swabian Jura's southern edge, in Southern Germany.

Vogelherd Cave: The Vogelherd Cave (German: 'Vogelherdhöhle' , or simply "Vogelherd") is located in the eastern Swabian Jura, south-western Germany.  This limestone karst cave came to scientific and public attention after the 1931 discovery of the Upper Palaeolithic "Vogelherd figurines", attributed to paleo-humans of the Aurignacian culture.  These miniature sculptures made of mammoth ivory rank among the oldest uncontested works of art of mankind.  In 2017 the site became part of the UNESCO World Heritage Site "Caves and Ice Age Art in the Swabian Jura".

Speleonaut: Speleonaut (named from the Greek words for "cave" and "sailor") is the submersible used by the cave diver Jochen Hasenmayer.  After the 1989 decompression accident that left his legs paralyzed, Hasenmayer designed the "Speleonaut" with his friend Konrad Gehringer in order to continue exploring the Blauhöhle cave system, which begins at the base of the Blautopf spring in the Swabian Jura mountain range.  The "Speleonaut" is 72 cm wide and has nine engines, making it easy to maneuver in all directions.  It is the first submarine designed specifically for the exploration of caves.  According to Hasenmayer, the "Speleonaut" has been tested in Lake Constance to a depth of 105 m and has a design limit of 180 m .

Reutlingen–Schelklingen railway: The Reutlingen–Schelklingen railway or Swabian Jura Railway (German: "Schwäbische Albbahn") is a 58.25 kilometre long branch line from Reutlingen to Schelklingen, which crosses the Swabian Jura in southern Germany.  Its route no.  is 4620.  The section from Reutlingen to Honau is also known as the Echaz Railway ("Echazbahn") or Echaz Valley Railway ("Echaztalbahn").  The 15.28 kilometre long northern section from Reutlingen to Kleinengstingen is closed nowadays, this section has been largely converted into a rail trail.

Blauhöhle: The Blauhöhle is the largest cave system in the Swabian Alps in southern Germany.  The Blauhöhle presumably originated in a time when the Danube still flowed through the Blau valley.  Since the shifting of the Danube, several small rivers, the Schmiech, the Ach, and the Blau, have flowed through this valley.  The cave system begins about 21 meters under water at the base of the Blautopf.  It continues west and northwest, rising and falling several times until after a horizontal distance of about 1200 m it comes above the level of ground water and opens into the second big air-filled chamber.  The maximum depth of the cave under water is 42 m .

Supporting paragraphs: Speleonaut Blautopf
Answer: Blautopf