Telescopic submarine

A telescopic submarine, comprising:

• a front submarine unit (1), a rear submarine unit (2), and a lift tower (3),
• wherein said front submarine unit (1) comprises a submarine bow (4), which is domed, a front submarine body (5), which is cylindrical, a first wedge-shaped keel (6) connected with a lower portion of said front submarine body (5), and a hydrocylinder (7), which is ring-shaped and connected with a rear end of said front submarine body (5), wherein a vertical section of said hydrocylinder (7) is in a shape of a ladder, a spacing ring (8) is provided on an end portion of said hydrocylinder (7), said hydrocylinder (7) is connected with a controlling valve (10) and a hydraulic pump (11) via a pipeline (9), and said controlling valve (10) and said hydraulic pump (11) are respectively connected with a hydraulic oil tank (12),
• wherein said rear submarine unit (2) comprises a rear submarine body (13), which is cylindrical, a piston (14), which is ring-shaped and connected with a front end of said rear submarine body (13), a submarine stern (15), which is cone-shaped and connected with a rear end of said rear submarine body (13), and a second wedge-shaped keel (16) connected with a lower portion of said rear submarine body (13), wherein a cross-sectional area of said second wedge-shaped keel (16) is smaller than a cross-sectional area of said first wedge-shaped keel (6), a first piston ring (17) is embedded in an outer surface of said piston (14), a second piston ring (18) is embedded in an inner surface of said piston (14), said piston (14) and said hydrocylinder (7) operate with each other slidingly, a propeller (19), a horizontal rudder (20) and a vertical rudder (21) are installed in said submarine stern (15), and an external thread sealing door (22) is installed on a top portion of said lift tower (3).