This is a nice vintage Certina DS Automatic from the ca. 1970's with a Certina 27 jewels caliber 25-651. There is some patina / oxidation on the dial which gives the vintage charm and value :). This is my turtle watch 🐢 (see caseback), the turtle on the DS series symbolize protection against water and shocks.
The DS (Double Security), in which the movement is enclosed in a kind of highly stable vault. The Certina DS were the first watches to increase shock protection and water resistance to 6 m (previous watches were set at 2.2 meters). The Certina DS watch was taken up the Himalayas by a team who climbed the Dhaulagiri and the watch withstood all changes in pressure and altitude.
Info about the specs of the Certina Cal. 25-651; here.
If you want to read more about the history of Certina; here.