How many species of sea turtles exist?

seven species exist in the world. The hawksbill (Eretmochelys imbricata), green (Chelonia mydas), leatherback (Dermochelys coriacea), loggerhead (Caretta caretta), kemp's ridley (Lepidochelys kempii), olive ridley (Lepidochelys olivacea), and the flatback (Natator depressus).